A353381 Number of divisors of n not in A353355.

0, 1, 1, 1, 1, 2, 1, 1, 1, 3, 1, 2, 1, 2, 2, 2, 1, 2, 1, 3, 3, 3, 1, 3, 1, 2, 1, 2, 1, 5, 1, 2, 2, 3, 2, 2, 1, 2, 3, 4, 1, 5, 1, 3, 2, 3, 1, 4, 1, 3, 2, 2, 1, 3, 3, 3, 3, 2, 1, 5, 1, 3, 3, 2, 2, 5, 1, 3, 2, 5, 1, 3, 1, 2, 2, 2, 2, 5, 1, 6, 2, 3, 1, 5, 3, 2, 3, 4, 1, 5, 3, 3, 2, 3, 2, 4, 1, 2, 2, 3, 1, 5, 1, 3, 5

Offset

1,6

Links

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

Index entries for sequences computed from indices in prime factorization

Formula

a(n) = Sum_{d|n} 1-A353380(d).

a(n) = A000005(n) - A353382(n).

a(p) = 1 for all primes p.

a(n) = a(A003961(n)) = a(A348717(n)), for all n >= 1.

Prog

(PARI)
A332823(n) = { my(f = factor(n), u=(sum(k=1, #f~, f[k, 2]*2^primepi(f[k, 1]))/2)%3); if(2==u, -1, u); };
A353354(n) = sumdiv(n, d, A332823(d));
A353380(n) = (0==A353354(n));
A353381(n) = sumdiv(n, d, !A353380(d));

Crossrefs

Cf. A000005, A003961, A048675, A332823, A348717, A353352, A353354, A353355, A353380, A353382.

Sequence in context: A175307 A324825 A316557 * A032436 A360615 A280274

Adjacent sequences: A353378 A353379 A353380 * A353382 A353383 A353384

Keyword

nonn

Author

Antti Karttunen, Apr 19 2022

Status

approved