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A274574 Central terms of triangle A274570. 4
1, 2, 39, 2188, 247465, 47290506, 13732594855, 5645761143968, 3124313624563281, 2240929551882269890, 2023001689428835457551, 2245340983227461222262600, 3005921392102922941037743561, 4777188534537036418050441999458, 8892651921874938986718539648539335, 19167346139929272962512547586833106016, 47363669252787891219004826832547428944065, 133017373943189884985366059167726505579520322, 421334607602498277189468756234637306051458074191, 1495034827615578030423476599123008111000477082402040, 5906697677063490360959940664316005473632429506949424681 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Triangle A274570 transforms diagonals in the array A274390 of coefficients of successive iterations of Euler's tree function (A000169).

LINKS

Table of n, a(n) for n=0..20.

PROG

(PARI) {T(n, k)=local(F=x,

LW=serreverse(x*exp(-x+x*O(x^(n+2)))), M, N, P, m=max(n, k));

M=matrix(m+3, m+3, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, LW)); polcoeff(F, c));

N=matrix(m+1, m+1, r, c, M[r, c]);

P=matrix(m+1, m+1, r, c, M[r+1, c]);

(n-k)!*(P~*N~^-1)[n+1, k+1]}

/* Print triangle : */

for(n=0, 10, for(k=0, n, print1(T(n, k), ", ")); print(""))

/* Print this sequence, which is central terms */

for(n=0, 20, print1(T(2*n, n), ", "))

CROSSREFS

Cf. A274570, A274571, A274572, A274573.

Sequence in context: A266863 A245053 A177773 * A212615 A247878 A232086

Adjacent sequences:  A274571 A274572 A274573 * A274575 A274576 A274577

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Jun 28 2016

STATUS

approved

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Last modified November 22 03:40 EST 2019. Contains 329386 sequences. (Running on oeis4.)