A373491 a(n) = 1 if A059975(n) and A083345(n) are both multiples of 3, otherwise 0, where A059975 is fully additive with a(p) = p-1, and A083345 is the numerator of the fully additive function with a(p) = 1/p.

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

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = [A373377(n) == 0 (mod 3)], where [ ] is the Iverson bracket.

a(n) <= A373493(n).

Prog

(PARI)
A059975(n) = {my(f = factor(n)); sum(i = 1, #f~, f[i, 2]*(f[i, 1] - 1)); };
A083345(n) = { my(f=factor(n)); numerator(vecsum(vector(#f~, i, f[i, 2]/f[i, 1]))); };
A373491(n) = (!(A059975(n)%3) && !(A083345(n)%3));

Crossrefs

Characteristic function of A373492.

Cf. A059975, A083345, A373377, A373493.

Sequence in context: A015626 A015920 A014744 * A373588 A373596 A373472

Adjacent sequences: A373488 A373489 A373490 * A373492 A373493 A373494

Keyword

nonn

Author

Antti Karttunen, Jun 10 2024

Status

approved