A373977 a(n) = 1 if n is a nonprime of the form 3*k + 1, otherwise 0.

1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 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, 3]==1]; Array[a, 121] (* Stefano Spezia, Jun 25 2024 *)

Prog

(PARI) A373977(n) = (!isprime(n) && 1==(n%3));

Crossrefs

Characteristic function of A291745.

Cf. also A373978.

Sequence in context: A224877 A389656 A178600 * A359170 A014702 A015395

Adjacent sequences: A373974 A373975 A373976 * A373978 A373979 A373980

Keyword

nonn

Author

Antti Karttunen, Jun 25 2024

Status

approved