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%I #11 Jul 31 2019 10:49:49
%S 1,10,45,142,362,780,1561,2762,4808,7570,12034,17482,26072,35884,
%T 50909,67012,92111,116950,155720,193564,250914,304244,389286,461654,
%U 578952,680944,839304,970094,1188924,1354164,1637145,1858344,2215866,2485068
%N Convolution square of A001157 (the sum of squared divisors).
%H Amiram Eldar, <a href="/A175705/b175705.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = Sum_{k=1..n} A001157(k)* A001157(n+1-k).
%F G.f.: (1/x)*(Sum_{k>=1} k^2*x^k/(1 - x^k))^2. - _Ilya Gutkovskiy_, Jan 01 2017
%p with(numtheory): T:=array(1..200):for p from 1 to 200 do: liste:=divisors(p) :s2:=sum(liste[i]^2,i=1..nops(liste)):T[p] :=s2 :od : for n from 1 to 100 do: printf(`%d, `, sum (T[k]*T[n+1-k],k=1..n)):od:
%t a[n_] := Sum[DivisorSigma[2, k] * DivisorSigma[2, n + 1 - k], {k, 1, n}]; Array[a, 34] (* _Amiram Eldar_, Jul 31 2019 *)
%Y Cf. A001157.
%K nonn
%O 1,2
%A _Michel Lagneau_, Aug 10 2010
%E Definition slightly rephrased by _R. J. Mathar_, Aug 19 2010
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