A201779 - OEIS

A201779

G.f. A(x) satisfies A(x/(1-x))=x*(1+A(x))/(1-A(x)-A(x)^2).

1, 1, 2, 5, 11, 23, 52, 120, 247, 534, 1433, 2540, 3264, 30169, 19123, -363258, 2951500, -1601367, -99325484, 799655132, -1194225728, -32599353806, 345568196667, -1063427879019, -13137091603516, 205598895773140, -1103275663780401

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..27.

FORMULA

a(n)=T(n,1), T(n,m)=sum(k=1..n-m, T(n-m,k)*sum(binomial(i+m-1,m-1)*binomial(i+m,k-i),i,0,k)-binomial(n-1,k+m-2)*T(k+m-1,m)), n>m, T(n,n)=1.

PROG

(Maxima)

array(BB, 100, 100);

fillarray (BB, makelist (-1, i, 1, 1000));

T(n, m):=if BB[n, m]=-1 then BB[n, m]:(if n=m then 1 else sum(T(n-m, k)*sum(binomial(i+m-1, m-1)*binomial(i+m, k-i), i, 0, k)-binomial(n-1, k+m-2)*T(k+m-1, m), k, 1, n-m)) else BB[n, m];

makelist(T(n, 1), n, 1, 27);

CROSSREFS

Sequence in context: A018112 A274489 A192415 * A067149 A354150 A344782

Adjacent sequences: A201776 A201777 A201778 * A201780 A201781 A201782

KEYWORD

sign

AUTHOR

Vladimir Kruchinin, Dec 04 2011

STATUS

approved