login
A076401
Sum of divisors of n-th 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
OFFSET
1,2
LINKS
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
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 09 2002
STATUS
approved