A139055 - OEIS

%I #10 Jan 07 2020 09:07:40

%S 0,1,1,1,1,1,9,14,42,54,64,19,1,105,196,153,183,191,536,333,1548,1014,

%T 257,1649,1282,4284,3326,2870,1483,7500,4390,4419,7641,9866,7461,1,

%U 5435,9097,38511,50214,29913,33874,41283,22041,47954,109338,107806,77175,61579,129998

%N Sum of proper divisors of the number of partitions of n.

%H Amiram Eldar, <a href="/A139055/b139055.txt">Table of n, a(n) for n = 1..10000</a> (calculated from the b-files at A000041 and A001065)

%F a(n) = A001065(A000041(n)).

%e a(7) = 9 because the number of partitions of 7 is 15 and the sum of proper divisors of 15 is equal to 1 + 3 + 5 = 9.

%t s[n_] := DivisorSigma[1, n] - n; Array[s[PartitionsP[#]] &, 50] (* _Amiram Eldar_, Jan 07 2020 *)

%o (PARI) a(n) = my(p=numbpart(n)); sigma(p) - p; \\ _Michel Marcus_, Jan 07 2020

%Y Cf. A000041, A001065, A139041.

%K nonn

%O 1,7

%A _Omar E. Pol_, Apr 16 2008