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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 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.)