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A135070
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a(n) = [x^(2^n+n-2)] (x + x^2 + x^4 + x^8 + ... + x^(2^n))^n for n>=2.
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4
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1, 3, 18, 70, 600, 4956, 52528, 358128, 6654600, 79967800, 1453049400, 16239408120, 392541718660, 5252687631660, 108961629396480, 1395025456201408, 62831427044385384, 1223872353413404344
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OFFSET
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2,2
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LINKS
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FORMULA
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n(n-1)/2 divides a(n): A135071(n) = a(n)/[n(n-1)/2] for n>=2.
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MATHEMATICA
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f[x_, n_] := (Sum[x^(2^k), {k, 0, n}])^n; Table[Coefficient[f[x, n], x^(2^n + n - 2)] , {n, 2, 10}] (* G. C. Greubel, Sep 22 2016 *)
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PROG
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(PARI) {a(n)=if(n<2, 0, polcoeff(sum(j=0, n, x^(2^j)+O(x^(2^n+n)))^n, 2^n+n-2))}
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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