A105349 Characteristic sequence for the Pell numbers.

1, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset: 0

Author

Paul Barry, Apr 01 2005

Keywords

• easy
• nonn

Links

• Index entries for characteristic functions.

Crossrefs

Cf. A000129.

Programs

Mathematica

a[n_] := If[Or @@ (IntegerQ[Sqrt[#]]& /@ (2*n^2 + {-1, 1})), 1, 0]; Array[a, 100, 0] (* Amiram Eldar, Jun 20 2024 *)

Formula

G.f.: Sum_{k>=0} x^A000129(k).