A133436 Generated by a kind of sieve (see Comments lines).

2, 5, 7, 11, 14, 18, 21, 27, 29, 34, 40, 42, 50, 53, 57, 62, 69, 72, 79, 84, 89, 93, 103, 105, 110, 119, 124, 131, 135, 145, 149, 156, 160, 170, 176, 179, 185, 194, 200, 207, 214, 218, 231, 234, 242, 248, 259, 263, 270, 277, 281, 293, 300, 305, 315, 322, 329, 339

Offset

1,1

Comments

Start with the list of positive integers.

Call the current version of the list b(1), b(2), b(3), ...

Remove b(1) = 1 and renumber the terms.

Remove b(2) and b(2+1) from the remaining list and renumber the terms.

Remove b(3), b(3+2) and b(3+2+1) from the remaining list and renumber the terms.

Remove b(4), b(4+3), b(4+3+2) and b(4+3+2+1) from the remaining list and renumber the terms.

Repeat the process. What is left forms the sequence.

Links

Austin C. Green and T. D. Noe, Table of n, a(n) for n=1..1000 (b-file extended and corrected).

Example

a(3) = 7 because:
integer 1 is eliminated in the first round,
integers 3 and 4 are eliminated in the second round and
integers 6, 8 and 9 are eliminated in the third round.
This leaves the numbers 2, 5, 7...

Mathematica

lg = 1000; max = (lg+1)^2; Clear[p, bb, n]; p[1] = {{1}}; p[n_] := p[n] = Prepend[p[n-1]+n, {n}]; bb[n_] := bb[n] = Delete[bb[n-1], p[n]]; bb[0] = Range[max]; bb[n=1]; While[n <= lg && bb[n][[;; lg]] != bb[n-1][[;; lg]], n++]; A133436 = bb[n][[;; lg]] (* Jean-François Alcover, Mar 24 2016 *)

Crossrefs

Sequence in context: A236762 A327952 A099835 * A363244 A351897 A184676

Adjacent sequences: A133433 A133434 A133435 * A133437 A133438 A133439

Keyword

nonn,nice

Author

Austin C. Green (whyphi(AT)gmail.com), Nov 25 2007

Status

approved