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 A152057 #16 Jun 07 2025 04:16:34
%S A152057 0,0,3,7,8,31,10,127,25,80,45,112,28,8191,173,189,282,131071,102,
%T A152057 524287,91,471,798,178528,286,2433,10925,262737,320,3425,534,
%U A152057 2147483647,65819,599598,174765,123150,266,616318400,699053,129646,61789,164524720,5936
%N A152057 Sum of the distinct prime factors of 2^n-1.
%H A152057 Amiram Eldar, <a href="/A152057/b152057.txt">Table of n, a(n) for n = 0..1206</a> (terms 0..500 from Robert Israel)
%F A152057 a(n) = A008472(A000225(n)). - _Robert Israel_, Jan 14 2021
%p A152057 sopf:= n -> convert(numtheory:-factorset(n),`+`):
%p A152057 seq(sopf(2^n-1),n=0..100); # _Robert Israel_, Jan 14 2021
%t A152057 Table[Sum[FactorInteger[2^n - 1][[m]][[1]], {m, 1, Length[FactorInteger[2^n - 1]]}], {n, 0, 50}]
%Y A152057 Cf. A000225, A008472, A046800, A075708.
%Y A152057 Row sums of A060443.
%K A152057 nonn
%O A152057 0,3
%A A152057 _Roger L. Bagula_, Nov 22 2008
%E A152057 Edited by _N. J. A. Sloane_, Nov 26 2008