login
This site is supported by donations to The OEIS Foundation.

 

Logo

Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS".
Other ways to donate

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified November 21 16:27 EST 2017. Contains 295003 sequences.