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User:Andrey Zabolotskiy

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Андрей Заболотский, Andrei Zabolotskii.

Mathematician at the Open University, UK.

If I commented on your sequence draft, you replied, my answer is expected, but I don't answer for three days, please do not hesitate to wiki-mail me.

I write about the OEIS.

OEIS contributions, including:

  • new sequences:
  • contributions to miscellaneous nice sequences invented by other people (this list not only shows my contributions, which are often minor, but also shows what sequences I consider really nice or useful):
    • A275302-A275305, related to Langton's ant on triangular lattice, by my pupil Oleg Nikulin;
    • A275667, cellular automaton on triangular tiling, by my pupil Alexey Kovba;
    • corrections and extensions from external sources for sequences related to counting knots and links such as A002863 and A049344;
    • programs for Conway's enumeration of rational knots A122495 and links A173637 (also extension of A018240, contributions to A277740);
    • nested log formula for A278813, A278452, and related sequences;
    • a program for A277795, Equisetum-like graphs;
    • corrections and program for A267794, relative of van Eck's sequence;
    • some terms and an asymptotic formula for A277828, number of coin tosses to get a run of consecutive identical result with probability >1/2;
    • exact programs for A291259 and A123690 together with Andres Cicuttin;
    • contributions to sequences related to Lyndon words and irreducible polynomials such as A074446;
    • realizing that A132101 is a 1D analog of A250001;
    • contributions to A282390, the tripling polyominoes;
    • contribution to A089618, „a Khinchin sequence“;
    • a term for A283075, times measurable by burning ropes;
    • program for A093914, the curling number of the Thue-Morse sequence;
    • program for A287150, the fairest turn sequence for 3 players, which is in some sense a generalization of the Thue-Morse sequence;
    • a simple formula connecting A335358 and A335359, the coordinates of the points of the Koch polyline, conjectured by me and later refined and proved by my pupil Artem Litvinov;
    • illustration for A003442, rooted dissections of n-gon;
    • corrections, programs, extensions for A112410 and related sequences, carbon skeletons with rings;
    • minor corrections to sequences related to the functional equation a(a(x)) = exp(x) − 1, see A052104;
    • extension and cleanup in A164950 related to the Sprouts game;
    • contributions to A278566, related to monstrous moonshine;
    • contributions to sequences counting „chemically relevant“ graphs such as A215622 or A167227;
    • a formula for A006082, number of flat trees;
    • contributions to A296516, the number of terms in a recursively defined polynomial;
    • contributions to A228369 and A296772, the compositions of integers (see also below), also to A048793, subsets of natural numbers;
    • contribution to A001998 (I found this sequence when counted by how many ways can we stack n layers of graphene commensurately);
    • correction to A091159, nets for n-hypercube;
    • corrections and extensions from literature and databases to sequences counting lattice polytopes such as A127709, A187015, or A105232;
    • contributions to sequences counting lattices and related objects such as A097584 or A054907, see also the mention of the space groups below;
    • more terms for sequences A005368 and A259976 related to representations of some permutation groups;
    • formulas and corrections for A117966 and A244042 and a program for A059095, related to the balanced ternary representation of integers;
    • a comment for A108918, reversed binary words in reversed lexicographic order, and observations about A118319, the inverse permutation;
    • extensions from literature for sequences counting algebraic systems such as A127707 and A181769;
    • contributions to A153036, related to the Stern-Brocot tree;
    • clarifications for A085469 (also A108778), A181152, and A182566, the Madelung constants;
    • clarifications for A242674 and A246665, constants related to the secretary problem;
    • contributions to A146978, related to the Rudvalis group;
    • extension of A318271, the Bridge and Torch problem;
    • contributions to Zorach additive triangle A035312 and related sequences, including A136561;
    • contributions to A074031-A074035 and other sequences related to irreducible polynomials over GF(4);
    • investigation of A280984, guarding dominoes problem;
    • combinatorial interpretation for A302335 and A302336, related to cycles in a grid;
    • program for A189226, curvatures in an Apollonian circle packing;
    • contributions to theta series such as A217511;
    • contributions to A171108 and other sequences of Severi degrees;
    • contributions to A274369 and other Langton's ant related sequences;
    • crossrefs for A341319, related to gerrymandering;
    • collecting rows, columns and diagonals of A000027 written as a table as crossrefs for A055998;
    • identifying the „hypertriangular lattice“ from A344126 as the lcy net;
    • updates to A218537, rigid regular polygons;
    • a comment relating the triangles A099238 and A329146;
    • minor contributions to A180603 related to Brillouin zones;
    • a b-file for A039926, random digits (sic!);
    • empirical connection between a shuffling and cyclotomic polynomials, noticed in an abandoned draft and added to A289386;
    • various formulas discovered using OEIS explorer and the wonderful Sequence Machine;
    • interesting trivia: A051037 is related to bamboo, A074650 was thought to be related to DNA;
  • physics:
    • I went through all sequences related to classification of n-dimensional space groups, including magnetic space groups, and contributed to some of them. This started from A006227(5), number of 5-dimensional space groups, and culminated in A293060-A293063 (see above);
    • removing heresy from A003673 and A005600, the fine-structure constant, as well as from other sequences;
    • another formula for A260832, „numbers 2(n)“, which actually arose in my research;
    • contributions to A019694, 2π/5, and other sequences in connection with the redefinition of SI;
    • I went through all decimal expansions of constants of nature I could find and fixed the offsets in several of them;
    • dropping excessive digits of constants of nature;
    • references, extensions from literature, and sometimes formulas for many old sequences related to thermodynamics such as A002907, A003200, A001393, or A010571, or (surprisingly) polyominoes, such as A216820;
  • preparing the list of matches between OEIS sequences and RCSR coordination sequences;
  • editorial work:
    • routine, including especially reviewing, recycling, and fixing dead links;
    • making some places in the OEIS guidelines more clear and closer to the current practice;
    • killing (with keyword dead) many old incorrect sequences, merging duplicates;
    • editing of A054434, the Rubik's cube related sequence with unknown definition (I am particularly proud of solving this mystery);
    • a program and discussion of binary Barker codes A276690;
    • crossrefs between different versions of the same sequences, such as A035607 (coordination sequences for hypercubic lattices) and A066099 (compositions of integers);
    • discussion about the balance between chemical and mathematical definitions of A134818;
    • clarifications to A040004 and A287286, related to Waring's problem mod n (it took time to verify that the difference in one term only is not a mistake);
    • help with sequences from new authors such as A290772 (some cyclic Gray codes) and A292046 (related to Elias omega coding);
    • investigation of spherical curves A264759 together with main contribution from Robert Coquereaux;
    • an explanatory comment to A220952, Knuth's base-5 twisted enumeration of the nonnegative integers;
    • subtle corrections to A180620 and A231100, legs of primitive Pythagorean triples;
    • a simpler definition to A072833 (probably equivalent to the old one, no difference in the known terms);
    • fixes to PARI programs for many sequences related to binary quadratic forms;
    • comments about handling outdated content from star contributors in the discussion of A285357;
    • a comment about uninteresting conjectures in the discussion of A058077;
    • removing inappropriate unkn keyword;
    • fixing confusing names of sequences and sometimes whole obsc sequence entries: compare A162997 before and after;
    • fixing incorrect crossrefs;
    • removing email addresses of deceased contributors;
  • etc.

The primary mechanism of decision-making in the OEIS community is NJAS ex machina.

Beware of the imp!