A073807 Number of divisors of sum of cube of divisors.

1, 3, 6, 2, 12, 18, 8, 12, 2, 20, 18, 12, 8, 24, 36, 4, 32, 6, 24, 24, 24, 30, 36, 72, 4, 24, 32, 16, 24, 60, 36, 16, 60, 48, 60, 4, 16, 72, 24, 80, 24, 72, 24, 36, 24, 60, 60, 24, 8, 12, 96, 16, 20, 96, 80, 96, 50, 40, 72, 72, 16, 108, 16, 8, 54, 100, 12, 64, 108, 100, 32, 24

Offset

1,2

Comments

a(n) = 2 for n in A063783. - Robert Israel, Jul 12 2023

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Formula

a(n) = A000005(A001158(n)).

Example

For n=10: D={1,2,5,10}, 1+8+125+1000=1134, divisors(1134)={1,2,3,6,7,9,14,18,21,27,42,54,63,81,126,162,189,378,567,1134} so a(10)=20.

Maple

f:= n -> numtheory:-tau(numtheory:-sigma[3](n)):
map(f, [$1..100]); # Robert Israel, Jul 12 2023

Mathematica

Table[DivisorSigma[0, DivisorSigma[3, n]], {n, 80}] (* Harvey P. Dale, Dec 13 2011 *)

Prog

(PARI) a(n) = numdiv(sigma(n, 3)); \\ Michel Marcus, Jul 13 2023

Crossrefs

Cf. A000005, A001158, A062068, A063783, A073802-A073813.

Sequence in context: A210199 A268717 A002516 * A378524 A345671 A090774

Adjacent sequences: A073804 A073805 A073806 * A073808 A073809 A073810

Keyword

nonn

Author

Labos Elemer, Aug 13 2002

Status

approved