This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A076401 #14 Feb 16 2025 08:32:47
%S A076401 1,7,15,13,31,31,40,63,91,57,127,121,217,133,156,255,403,183,399,600,
%T A076401 403,364,511,307,847,400,381,961,741,931,1023,553,1651,781,1281,1093,
%U A076401 1767,871,2821,993,2340,2047,1729,2149,1767,3751,1464,1407,2667,2379
%N A076401 Sum of divisors of n-th perfect power.
%H A076401 Amiram Eldar, <a href="/A076401/b076401.txt">Table of n, a(n) for n = 1..10000</a>
%H A076401 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PerfectPower.html">Perfect Powers</a>.
%H A076401 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/DivisorFunction.html">Divisor Function</a>.
%F A076401 a(n) = A000203(A001597(n)).
%p A076401 N:= 10^4: # to use all perfect powers <= N
%p A076401 L:= sort(convert({seq(seq(i^k, i=1..floor(N^(1/k))), k=2..ilog2(N))},list)):
%p A076401 map(numtheory:-sigma,L); # _Robert Israel_, Oct 02 2014
%o A076401 (PARI) lista(nn) = {for (n=1, nn, if ((n==1) || ispower(n), print1(sigma(n), ", ")););} \\ _Michel Marcus_, Oct 02 2014
%Y A076401 Cf. A000203, A001597, A076400.
%K A076401 nonn
%O A076401 1,2
%A A076401 _Reinhard Zumkeller_, Oct 09 2002