A353477 a(n) = 1 if n is a semiprime of the form 4k+1, otherwise 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, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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, 0, 0, 0, 0, 1, 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, 1

Offset

1

Links

Antti Karttunen, Table of n, a(n) for n = 1..65537

Index entries for characteristic functions

Formula

a(n) = [A001222(n) == 2] * && [A010873(n) == 1], where [ ] are the Iverson brackets.

a(n) = A353480(n) - A353479(n).

Mathematica

Table[If[PrimeOmega[n]==2&&Mod[n, 4]==1, 1, 0], {n, 130}] (* Harvey P. Dale, Mar 03 2024 *)

Prog

(PARI) A353477(n) = ((2==bigomega(n)) && (1==(n%4)));

Crossrefs

Characteristic function of A108181.

Cf. A001222, A010873, A064911, A353478, A353479, A353480.

Sequence in context: A297038 A353639 A353569 * A044939 A373973 A371084

Adjacent sequences: A353474 A353475 A353476 * A353478 A353479 A353480

Keyword

nonn

Author

Antti Karttunen, Apr 22 2022

Status

approved