A323069 Number of divisors d of n such that A049820(d) > 1 and A049820(d) is also a divisor of n.

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

Offset

1,12

Links

Antti Karttunen, Table of n, a(n) for n = 1..10080

Formula

Sum_{d|n} [A049820(d) > 1 and A049820(d)|n], where [ ] is the Iverson bracket.

a(n) <= A323068(n).

a(n) >= A322358(n).

Prog

(PARI) A323069(n) = sumdiv(n, d, my(t=(d-numdiv(d))); ((t>1)&&!(n%t)));

Crossrefs

Cf. A000005, A049820, A322358, A323068.

Sequence in context: A161369 A151843 A276422 * A325334 A280287 A147696

Adjacent sequences: A323066 A323067 A323068 * A323070 A323071 A323072

Keyword

nonn

Author

Antti Karttunen, Jan 05 2019

Status

approved