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%I #19 Jan 15 2015 20:39:52
%S 1,2,4,8,20,26,28,29,39,41,129,430,526,591,655,731,1388,1622,2249,
%T 3734,6841,18752,18772,21332,35017,37337,53173,105557,113377,124753,
%U 419029,614153,824149,829333,2192923,2369654,2538915,3059853,3388115,3479244,3557183
%N Numbers n such that sigma(n) is a partition number.
%H Robert G. Wilson v, <a href="/A252891/b252891.txt">Table of n, a(n) for n = 1..65</a>
%e 26 is in the sequence because the sum of divisors of 26 is 1 + 2 + 13 + 26 = 42 and 42 is a partition number because the number of partitions of 10 is equal to 42.
%t (* To extend the search beyond 50400, be sure to increase the length of partNums accordingly *) partNums = PartionsP[Range[50]]; Select[Range[100], MemberQ[partNums, DivisorSigma[1, #]] &] (* _Alonso del Arte_, Dec 24 2014 *)
%Y Cf. A000041, A000203.
%K nonn
%O 1,2
%A _Omar E. Pol_, Dec 24 2014
%E a(11)-a(16) from _Alonso del Arte_, Dec 24 2014
%E More terms from _Michel Marcus_, Dec 27 2014
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