A374222 a(n) = 1 if sigma(n) and sopfr(n) are both multiples of 3, otherwise 0, where sigma is the sum of divisors, and sopfr is the sum of prime factors with repetition.

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

Offset

1

Links

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

Index entries for characteristic functions

Formula

a(n) = A079978(A374126(n)).

a(n) = (1-A353815(n)) * A373371(n).

a(3*n) = a(n).

Prog

(PARI)
A001414(n) = ((n=factor(n))[, 1]~*n[, 2]);
A374222(n) = (!(sigma(n)%3) && !(A001414(n)%3));

Crossrefs

Characteristic function of A374223.

Cf. A000203, A001414, A079978, A353815, A373371, A374126.

Sequence in context: A293162 A115790 A025460 * A169673 A101605 A358753

Adjacent sequences: A374219 A374220 A374221 * A374223 A374224 A374225

Keyword

nonn

Author

Antti Karttunen, Jul 08 2024

Status

approved