

A076401


Sum of divisors of nth perfect power.


2



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
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OFFSET

1,2


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.


FORMULA

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


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


PROG

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


CROSSREFS

Cf. A000203, A001597, A076400.
Sequence in context: A290621 A290629 A234861 * A180114 A204740 A244536
Adjacent sequences: A076398 A076399 A076400 * A076402 A076403 A076404


KEYWORD

nonn


AUTHOR

Reinhard Zumkeller, Oct 09 2002


STATUS

approved



