A105624 Column 2 of triangle A105623.

1, 3, 19, 167, 1831, 23843, 358339, 6097607, 115840951, 2430329603, 55812650419, 1392737182247, 37528377195271, 1086086115808163, 33600297897404899, 1106632150406054087, 38659524289511283991, 1427864216163041265923

Offset

0,2

Comments

A105623 equals the matrix square-root of triangle A105615.

Links

Table of n, a(n) for n=0..17.

Prog

(PARI) {a(n)=local(R, M=matrix(n+3, n+3, m, j, if(m>=j, if(m==j, 1, if(m==j+1, -2*j, polcoeff(1/sum(i=0, m-j, (2*i)!/i!/2^i*x^i)+O(x^m), m-j)))))^-1); R=(M+M^0)/2; for(i=1, floor(2*log(n+2)), R=(R+M*R^(-1))/2); return(if(n<0, 0, R[n+3, 3]))}

Crossrefs

Cf. A105615, A105623.

Sequence in context: A215093 A201123 A260700 * A238640 A349253 A080835

Adjacent sequences: A105621 A105622 A105623 * A105625 A105626 A105627

Keyword

nonn

Author

Paul D. Hanna, Apr 16 2005

Status

approved