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A190878 E.g.f. exp(x/(1-x-x^4)). 1

%I

%S 1,1,3,13,73,621,6211,70393,884913,12534553,197772931,3429365061,

%T 64519103353,1309062244933,28518573321603,664268130978481,

%U 16466530506866401,432644339697987633,12007970879629419523,351062850914762411773,10783262700644774606121

%N E.g.f. exp(x/(1-x-x^4)).

%H Vincenzo Librandi, <a href="/A190878/b190878.txt">Table of n, a(n) for n = 0..125</a>

%F a(n) = n!*sum(m=0..n, sum(j=0..(n-m)/3, binomial(n-3*j-1,m-1)*binomial(n-m-3*j,j))/m!).

%o (Maxima)

%o a(n):=n!*sum(sum(binomial(n-3*j-1,m-1)*binomial(n-m-3*j,j),j,0,(n-m)/3)/m!,m,0,n);

%o (PARI) Vec(serlaplace(exp(x/(1-x-x^4+O(x^66))))) /* Joerg Arndt, May 24 2011 */

%K nonn

%O 0,3

%A _Vladimir Kruchinin_, May 23 2011

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Last modified August 3 13:39 EDT 2021. Contains 346438 sequences. (Running on oeis4.)