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A118979 O.g.f: -12*x^3/(-1+x)/(-1+2*x)/(-1+3*x) = -2-2/(-1+3*x)-6/(-1+x)+6/(-1+2*x) . 2
12, 72, 300, 1080, 3612, 11592, 36300, 111960, 342012, 1038312, 3139500, 9467640, 28501212, 85700232, 257493900, 773268120, 2321377212, 6967277352, 20908123500, 62736953400, 188236026012, 564758409672, 1694375892300 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

Negative of the determinant of a series of 3 X 3 matrices, related to Stirling's numbers of the second kind by a factor of 12 (cf. A000392, A028243).

LINKS

Table of n, a(n) for n=3..25.

Index entries for linear recurrences with constant coefficients, signature (6,-11,6).

FORMULA

Let M = {{1, 1, 1}, {2^n, 4, 2}, {3^n, 9, 3}}. Then a(n) = -Det[M]

a(n) = 6*(1-2^n)+2*3^n = 12*A000392(n).

MATHEMATICA

M = {{1, 1, 1}, {2^n, 4, 2}, {3^n, 9, 3}} a = Table[ -Det[M], {n, 3, 30}]

CROSSREFS

Cf. A000392, A028243.

Sequence in context: A010024 A008414 A052181 * A014970 A236967 A227022

Adjacent sequences:  A118976 A118977 A118978 * A118980 A118981 A118982

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, May 25 2006

EXTENSIONS

Edited by N. J. A. Sloane, Dec 13 2007

STATUS

approved

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Last modified August 18 18:04 EDT 2017. Contains 290732 sequences.