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.

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

1,2

Comments

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

Links

Table of n, a(n) for n=1..54.

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 *)

Crossrefs

Cf. A089781, A132426.

Sequence in context: A190402 A175300 A316699 * A154264 A370141 A194694

Adjacent sequences: A132422 A132423 A132424 * A132426 A132427 A132428

Keyword

nonn

Author

Leroy Quet, Aug 20 2007

Extensions

More terms from Stefan Steinerberger, Oct 21 2007

Status

approved