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%I #3 Mar 31 2012 13:21:57
%S 1,1,2,1,1,1,1,2,1,1,1,0,2,1,2,1,1,2,0,1,1,0,2,1,2,0,1,3,1,1,1,1,0,1,
%T 1,1,1,2,1,0,2,2,2,0,1,1,0,2,1,0,1,1,3,1,0,1,1,2,2,1,0,1,2,1,1,0,2,0,
%U 0,1,2,1,2,1,0,2,0,3,1,2,1,0,2,1,1,1,1,0,0,1,0,1,4,1,1,0,1,2,0,2,1,1,2,1
%N Number of ways of representing n as exactly 2 generalized pentagonal numbers.
%e a(7)=2 as we have 7+0=5+2
%o (PARI) { v=vector(101); v[1]=0; for (i=1,50, v[2*i]=i*(3*i-1)/2; v[2*i+1]=i*(3*i+1)/2); x=vector(500); for (a=1,50, for (b=a,50, if (v[a]+v[b]<500, x[v[a]+v[b]+1]++))); x }
%Y Cf. A001318 (generalized pentagonal numbers), A002107 (expansion of Product (1-x^k)^2, k=1..inf.), A093519 (A093518(n)=0).
%K nonn
%O 0,3
%A _Jon Perry_, Mar 29 2004
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