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A166885 Column 1 of triangle A166884. 3
1, 1, 3, 15, 114, 1159, 14838, 229401, 4159662, 86580636, 2034850425, 53303009286, 1539990513588, 48648616439496, 1668228105283302, 61715049142446537, 2450018515737072792, 103892256368706869356, 4686744256645813560957 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Triangle A166884 transforms diagonals in the triangle A166880 of coefficients in the successive iterations of x+x^2+x^3.

LINKS

Table of n, a(n) for n=1..19.

PROG

(PARI) {a(n)=local(F=x, M, N, P, m=n); M=matrix(m+2, m+2, r, c, F=x; for(i=1, r+c-2, F=subst(F, x, x+x^2+x^3+x*O(x^(m+2)))); 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]); (P~*N~^-1)[n+1, 1]}

CROSSREFS

Cf. A166880, A166884, A166886, A166887.

Sequence in context: A295758 A059849 A123853 * A082163 A331122 A190629

Adjacent sequences:  A166882 A166883 A166884 * A166886 A166887 A166888

KEYWORD

nonn

AUTHOR

Paul D. Hanna, Nov 21 2009

STATUS

approved

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Last modified February 29 05:25 EST 2020. Contains 332353 sequences. (Running on oeis4.)