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A306842 a(n) = Sum_{d|n} binomial(n,d)*binomial(n,n/d). 1

%I

%S 1,4,6,44,10,612,14,3936,7074,22700,22,339792,26,624652,2732760,

%T 6401232,34,45174204,38,220441080,309304842,325909628,46,7330314960,

%U 2822796950,6760390052,27417926304,78814587656,58,548150764560,62,1352747882944,2111872688706

%N a(n) = Sum_{d|n} binomial(n,d)*binomial(n,n/d).

%H Seiichi Manyama, <a href="/A306842/b306842.txt">Table of n, a(n) for n = 1..3000</a>

%F If p is prime, a(p) = 2*p.

%o (PARI) {a(n) = sumdiv(n, d, binomial(n, d)*binomial(n, n/d))}

%Y Cf. A100484, A174462.

%K nonn

%O 1,2

%A _Seiichi Manyama_, Mar 12 2019

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Last modified July 7 15:31 EDT 2020. Contains 335495 sequences. (Running on oeis4.)