A076991 a(1) = 1, a(2) = 2, a(n) = smallest positive integer not occurring earlier such that the sum of three successive terms is a square.

1, 2, 6, 8, 11, 17, 21, 26, 34, 4, 43, 53, 25, 3, 36, 10, 18, 72, 31, 41, 9, 14, 13, 22, 29, 30, 5, 46, 49, 74, 73, 78, 45, 102, 109, 113, 67, 16, 38, 27, 35, 19, 90, 12, 42, 115, 39, 15, 142, 68, 79, 177, 33, 114, 214, 156, 71, 62, 63, 44, 37, 40, 23, 58, 88, 50, 87, 7, 75

Offset

1,2

Links

Ivan Neretin, Table of n, a(n) for n = 1..10000

Mathematica

a = {1, 2}; Do[s = a[[-1]] + a[[-2]]; k = Floor[Sqrt[s]] + 1; While[MemberQ[a, k^2 - s], k++]; AppendTo[a, k^2 - s], {n, 3, 70}]; a (* Ivan Neretin, May 25 2015 *)

Crossrefs

Cf. A076093, A077396, A034175.

Sequence in context: A183173 A178931 A243184 * A130205 A054067 A250190

Adjacent sequences: A076988 A076989 A076990 * A076992 A076993 A076994

Keyword

nonn,look

Author

Amarnath Murthy, Oct 25 2002

Extensions

More terms from David Garber, Oct 30 2002

Status

approved