A295305 a(n) = tau(sigma(n)) - tau(n), where tau is the number of divisors (A000005) and sigma is the sum of divisors of n (A000203).

0, 0, 1, -1, 2, 2, 2, 0, -1, 2, 4, 0, 2, 4, 4, -3, 4, -2, 4, 2, 2, 5, 6, 4, -1, 4, 4, 2, 6, 4, 4, 0, 6, 4, 6, -5, 2, 8, 4, 4, 6, 4, 4, 6, 2, 8, 8, -4, 1, -2, 8, 0, 6, 8, 8, 8, 6, 8, 10, 4, 2, 8, 2, -5, 8, 7, 4, 6, 8, 7, 10, -4, 2, 4, 0, 6, 8, 8, 8, -2, -2, 8, 10, 0, 8, 8, 12, 10, 10, 0, 6, 10, 4, 11, 12, 6, 4, 0, 6, -5, 6, 8, 6, 8, 6

Offset

1,5

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Formula

a(n) = A062068(n) - A000005(n).

Mathematica

Table[DivisorSigma[0, DivisorSigma[1, n]]-DivisorSigma[0, n], {n, 110}] (* Harvey P. Dale, Oct 26 2020 *)

Prog

(PARI) A295305(n) = (numdiv(sigma(n)) - numdiv(n));

Crossrefs

Cf. A000005, A000203, A062068, A295306.

Cf. A037197 (positions of zeros), A073803 (of positive terms), A073804 (of negative terms).

Sequence in context: A056557 A342624 A302986 * A082900 A171958 A301735

Adjacent sequences: A295302 A295303 A295304 * A295306 A295307 A295308

Keyword

sign

Author

Antti Karttunen, Nov 21 2017

Status

approved