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%I #16 Aug 17 2019 15:45:53
%S 1,6,28,36,48,72,144,168,182,180,372,576,280,336,864,720,558,702,1120,
%T 1080,1024,1008,1296,2016,1178,1344,3600,2016,1320,2160,2304,3720,
%U 2736,1836,4704,4212,2736,2280,5040,6048,2604,4992,5588,4752,5304,3312
%N Sum of the divisors of pentagonal numbers.
%C See also: A000326 Pentagonal numbers: n(3n-1)/2. A000203 sigma(n) = sum of divisors of n. Also called sigma_1(n). A074285 Sum of the divisors of n-th triangular number. A117949 Indices of pentagonal numbers whose sum of divisors is square.
%H Amiram Eldar, <a href="/A117948/b117948.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = sigma(n(3n-1)/2), where sigma is the sum of divisors function. - _Emeric Deutsch_, Apr 15 2006
%e a(5)=48 because the divisors of 5*(3*5-1)/2=35 are 1,5,7 and 35, having sum 48.
%p with(numtheory): seq(sigma(n*(3*n-1)/2),n=1..46); # _Emeric Deutsch_, Apr 15 2006
%t Table[DivisorSigma[1,(n(3n-1))/2],{n,50}] (* _Harvey P. Dale_, Jul 05 2015 *)
%Y Cf. A000203, A000326, A074285, A117949.
%K easy,nonn
%O 1,2
%A _Jonathan Vos Post_, Apr 04 2006
%E a(0) removed by _Amiram Eldar_, Aug 17 2019
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