User:Georg Fischer

OEIS contributions and favorites

• Groups of recurrences:
  • Columns of the triangle A055277 Rooted trees with n nodes and k leaves, 1 <= k <= n.
  • A341862 Even term in the linear recurrence signature for numerators and denominators
• A hierarchy of permutations of the integers: A307407 (level 0), A322469 (level 1, my first sequence), A307048 (level 2), A160016 (level 3, existed)
  • auxiliary sequences, arithmetic progressions: A308681, A308709, A309523, A309791, A309702, A338186,
  • A338206 (inverse of A160016), A338207 (inverse A307048), A338208 (inverse of A322469)
• A220952 (base 5, main entry, "Hn" - Knuth's sequence generated by an adjacency matrix, and similiar FASS curves, A307403 ("Hs"), A307404 ("Ln"), A307405 ("Ls"), A307406 (number of variants in base 2*n+1), A128173 (base 3, "n"), A300857 (base 7)
• Continued fractions of sqrt(n):
  • A308778 Central element(s) in the period
  • A308780 First element of the period
  • A341862 Even term in the linear recurrence signature for numerators and denominators
• Miscellaneous:
  • A309589 Base 10 numbers sorted lexicographically, A309590 (inverse)
  • A308436 (exported from A028574)
  • A046816 Pascal's tetrahedron with G.f.: 1/(1-x-x*y-x*y*z); A189225 4-dimensional version of Pascal's triangle with G.f.: 1/(1-w-w*x-w*x*y-w*x*y*z)
  • A309589 Number subsets {0, ..., 10^k - 1} written in base 10; A309590 (inverse)
  • A337094 N(chi_n) for the irreducible characters chi_n of the Monster simple group
• cf. teherba.org

OEIS maintenance projects

• Broken link maintenance
• B-file check
• Colorized b-files
• Coincidences - search lists of similiar sequences
• Index updates
• Shared digits in squares, sequences A136nnn of Jonathan Wellons
• User:Terrel_Trotter,_Jr., restoration of the WTM (World of Trotter Math)
• Sean Irvine's jOEIS project (Java implementation of OEIS sequences), contributions to linear recurrences, continued fractions of sqrt(n) and other groups of sequences

Interests

Programming

• Java, database, web applications, programming languages (speaking ALGOL 60, FORTRAN, PL/1, Pascal, Simula 67, C, Perl, Java, XSLT, SQL, JavaScript, understanding COBOL)
• Web (xHTML, CSS, SVG, threejs.org)
• Symbolic computation (c.f. https://github.com/gfis/ramath)

Community Projects

• Wikipedia: de, en, fr
• OpenStreetMap

Number Theory

• Diophantine equations, especially power sums
• Fermat's lost proofs (except for FLT) with infinite descent

Other

• Link collection of Gravestones and commemorative plates of mathematicians and physicists, preferrably with formula
• Wikipedia contributions

CV

• 1947 born in Waldshut, southern Germany.
• 1968 - 1975 Studies of Mathematics in Freiburg, and Computer Science in München, Germany.
• 1976 Software engineer at Softlab GmbH, München
• 1977 - 1980 Assistant at the Department of Computer Science, Dortmund, Germany. PhD in Compiler Construction: Incremental LR(1) Parser Construction as an Aid to Syntactical Extensibility
• 1980 - 1985 Chief consultant again at Softlab GmbH
• 1986 - 1994 Owner and Technical CEO of punctum GmbH, Munich (with two partners)
• 1995 - 1998 Maintenance and marketing of converter software, mainly for floppy disk file structures and text processing formats
• 1999 - 2004 Freelancer in Y2K, ISIN, Euro conversion projects at Commerzbank; computer aided software analysis
• 2005 - 2012 Principal Database Engineer at Commerzbank AG, Frankfurt, Germany; software metadata analysis and display
• 2012 - retired
• 2017 - IT-related development projects: microfinance database in Madagascar, Java programming training on Java (Bekasi, Indonesia)
• today - living in D-79341 Kenzingen, South-West Germany. at the border of the Black Forest; speaking German, English and some French