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A105349
Characteristic sequence for the Pell numbers.
1
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
0,1
FORMULA
G.f.: Sum_{k>=0} x^A000129(k).
MATHEMATICA
a[n_] := If[Or @@ (IntegerQ[Sqrt[#]]& /@ (2*n^2 + {-1, 1})), 1, 0]; Array[a, 100, 0] (* Amiram Eldar, Jun 20 2024 *)
CROSSREFS
Cf. A000129.
Sequence in context: A261178 A204439 A204443 * A096606 A351114 A128190
KEYWORD
easy,nonn
AUTHOR
Paul Barry, Apr 01 2005
STATUS
approved