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A080171 a(n)=na(n-1)-(n-1)^2a(n-2), a(0)=1, a(1)=1. 1
1, 1, 1, -1, -13, -49, 31, 1981, 14329, 2177, -1138879, -12745369, -15140069, 1638512239, 25497843007, 61319246261, -4755906736399, -96548141561599, -363409501289471, 24376817341458127, 618727176794661571, 3242543776104642191, -201522721892143624609 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

COMMENTS

a(n) is the determinant of the n X n tridiagonal matrix M with m(i,j)=min(i,j).

LINKS

Table of n, a(n) for n=0..22.

FORMULA

E.g.f.: Exp[ArcTan[(-1+2z)/Sqrt[3]]/Sqrt[3]]*Exp[Pi/(6*Sqrt[3])]/Sqrt[1-z+ z^2]

MATHEMATICA

c=CoefficientList[Series[Exp[ArcTan[(-1+2z)/Sqrt[3]]/Sqrt[3]]*Exp[Pi/(6*Sqrt[3]]/Sqrt[1 - z + z^2], {z, 0, 25}], z]; For[n=0, n<26, n++; Print[c[[n]]*(n-1)! ]]

CROSSREFS

Sequence in context: A189349 A013200 A156694 * A303680 A304131 A304219

Adjacent sequences: A080168 A080169 A080170 * A080172 A080173 A080174

KEYWORD

easy,sign

AUTHOR

Mario Catalani (mario.catalani(AT)unito.it), Feb 06 2003

STATUS

approved

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Last modified December 6 21:00 EST 2022. Contains 358648 sequences. (Running on oeis4.)