A373978 a(n) = 1 if n is a nonprime of the form 4*k + 1, otherwise 0.

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

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..100000

Index entries for characteristic functions

Mathematica

a[n_]:=Boole[!PrimeQ[n]&&Mod[n, 4]==1]; Array[a, 121](* Stefano Spezia, Jun 25 2024 *)

Prog

(PARI) A373978(n) = (!isprime(n) && 1==(n%4));

Crossrefs

Characteristic function of A091113.

Cf. also A079260, A373977, A373979.

Sequence in context: A014057 A015689 A359160 * A326499 A104124 A347246

Adjacent sequences: A373975 A373976 A373977 * A373979 A373980 A373981

Keyword

nonn

Author

Antti Karttunen, Jun 25 2024

Status

approved