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A105616 Column 1 of triangle A105615. 2
1, 4, 26, 226, 2426, 30826, 451586, 7489426, 138722426, 2839238026, 63654973826, 1551919194226, 40888965122426, 1157981114051626, 35083865696279426, 1132449247218851026, 38800104353355372026, 1406432065083818193226 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Also equals column 0 of triangle A105623 (offset 1), where A105623 equals the matrix square-root of triangle A105615.

LINKS

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

PROG

(PARI) {a(n)=if(n<0, 0, (matrix(n+2, n+2, 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)[n+2, 2])}

CROSSREFS

Cf. A105615, A105623.

Sequence in context: A152407 A291847 A168448 * A293915 A107879 A066224

Adjacent sequences:  A105613 A105614 A105615 * A105617 A105618 A105619

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Apr 16 2005

STATUS

approved

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Last modified January 19 18:36 EST 2022. Contains 350466 sequences. (Running on oeis4.)