A379480 a(n) = 1 if n is twice a square, otherwise 0.

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

Offset

0

Links

Antti Karttunen, Table of n, a(n) for n = 0..100352

Index entries for characteristic functions.

Formula

a(n) = A093709(n) - A010052(n).

a(n) = A053866(n) - A010052(n), for n >= 1.

Mathematica

A379480[n_] := Boole[EvenQ[n] && IntegerQ[Sqrt[n/2]]]; Array[A379480, 100, 0] (* Paolo Xausa, Jan 23 2025 *)

Prog

(PARI) A379480(n) = (!(n%2) && issquare(n/2));

Crossrefs

Characteristic function of A001105.

Cf. A010052, A053866, A093709.

Sequence in context: A016334 A154271 A225569 * A087032 A236677 A190236

Adjacent sequences: A379477 A379478 A379479 * A379481 A379482 A379483

Keyword

nonn

Author

Antti Karttunen, Jan 19 2025

Status

approved