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User:Georgi Guninski/seqs/A180435

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A180435


a(n) = a(n-1)*2^n+n, a(0)=1


http://oeis.org/classic/A180435

Sequence

1, 3, 14, 115, 1844, 59013, 3776838, 483435271, 123759429384, 63364827844617, 64885583712887818, 132885675443994251275, 544299726618600453222412, 4458903360459574912797999117, 73054672657769675371282417532942


Offset

0,2

Formula

a(n+1) = (2^(n + 1) + 1)*a(n) - 2^n*a(n - 1) + 1.

a(n+1) = ((a(n - 2) + 4*a(n - 1) + 4)*a(n) - 2*a(n - 1)^2 - 4*a(n)^2 + a(n - 2) - 4*a(n - 1))/(a(n - 2) - 2*a(n - 1)).

a(n) = 2^(n*(n+1)/2) + sum_{k=1..n} 2^( (n+k+1)*(n-k)/2 ) * k. - Max Alwekseyev, Sep 05 2010



Program

(PARI) a(n)=if(n<=0, 1, a(n-1)*2^n+n )

Crossrefs