A076401 Sum of divisors of n-th perfect power.

1, 7, 15, 13, 31, 31, 40, 63, 91, 57, 127, 121, 217, 133, 156, 255, 403, 183, 399, 600, 403, 364, 511, 307, 847, 400, 381, 961, 741, 931, 1023, 553, 1651, 781, 1281, 1093, 1767, 871, 2821, 993, 2340, 2047, 1729, 2149, 1767, 3751, 1464, 1407, 2667, 2379

Offset: 1

Author

Reinhard Zumkeller, Oct 09 2002

Keywords

• nonn

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Perfect Powers.
• Eric Weisstein's World of Mathematics, Divisor Function.

Crossrefs

Cf. A000203, A001597, A076400.

Programs

Maple

N:= 10^4: # to use all perfect powers <= N
L:= sort(convert({seq(seq(i^k, i=1..floor(N^(1/k))), k=2..ilog2(N))},list)):
map(numtheory:-sigma,L); # Robert Israel, Oct 02 2014

PARI

lista(nn) = {for (n=1, nn, if ((n==1) || ispower(n), print1(sigma(n), ", ")););} \\ Michel Marcus, Oct 02 2014

Formula

a(n) = A000203(A001597(n)).