cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A132425 a(1)=1. a(2)=2. For n >= 3, a(n) is the smallest integer which is > a(n-1), is not coprime to a(n-1) and is such that a(n)-a(n-1) does not equal a(m)-a(m-1) for any m < n.

Original entry on oeis.org

1, 2, 4, 8, 14, 21, 24, 32, 42, 51, 63, 77, 88, 104, 117, 132, 150, 155, 175, 196, 218, 242, 268, 296, 326, 358, 392, 427, 469, 518, 554, 592, 629, 646, 665, 690, 713, 744, 771, 804, 843, 888, 928, 957, 1001, 1053, 1101, 1152, 1198, 1248, 1302, 1358, 1416, 1473
Offset: 1

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Author

Leroy Quet, Aug 20 2007

Keywords

Comments

Is {a(n+1)-a(n)} a permutation of the positive integers?

Crossrefs

Programs

  • Mathematica
    a = {1, 2}; For[n = 1, n < 1500, n++, n = a[[ -1]]; c = 0; While[c == 0, n++; If[GCD[n, a[[ -1]]] > 1, b = 0; For[j = 1, j < Length[a], j++, If[a[[j + 1]] - a[[j]] == n - a[[ -1]], b = 1]]; If[b == 0, AppendTo[a, n]; c = 1]]]]; a (* Stefan Steinerberger, Oct 21 2007 *)

Extensions

More terms from Stefan Steinerberger, Oct 21 2007