A017706 Denominator of sum of -21st powers of divisors of n.

1, 2097152, 10460353203, 4398046511104, 476837158203125, 609359740010496, 558545864083284007, 9223372036854775808, 109418989131512359209, 500000000000000000000, 7400249944258160101211, 11501279977342425366528

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• frac

Comments

Sum_{d|n} 1/d^k is equal to sigma_k(n)/n^k. So sequences A017665-A017712 also give the numerators and denominators of sigma_k(n)/n^k for k = 1..24. The power sums sigma_k(n) are in sequences A000203 (k=1), A001157-A001160 (k=2,3,4,5), A013954-A013972 for k = 6,7,...,24. - Ahmed Fares (ahmedfares(AT)my-deja.com), Apr 05 2001

Links

• G. C. Greubel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A017705.

Programs

Magma

[Denominator(DivisorSigma(21,n)/n^21): n in [1..20]]; // G. C. Greubel, Nov 05 2018

Mathematica

Table[Denominator[DivisorSigma[21, n]/n^21], {n, 1, 20}] (* G. C. Greubel, Nov 05 2018 *)

PARI

vector(20, n, denominator(sigma(n, 21)/n^21)) \\ G. C. Greubel, Nov 05 2018