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A128986 a(n) = (n^3 - n^2)*3^n. 1
0, 36, 486, 3888, 24300, 131220, 642978, 2939328, 12754584, 53144100, 214347870, 841802544, 3233287044, 12187005012, 45199057050, 165299408640, 597144113712, 2133912053412, 7552375012566, 26499561447600, 92260315250460 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
FORMULA
G.f.: 18x^2(2+3x)/(1-3x)^4. - R. J. Mathar, Dec 19 2008
a(n) = 12*a(n-1) - 54*a(n-2) + 108*a(n-3) - 81*a(n-4). - Vincenzo Librandi, Feb 11 2013
MATHEMATICA
LinearRecurrence[{12, -54, 108, -81}, {0, 36, 486, 3888}, 30] (* Vincenzo Librandi, Feb 11 2013 *)
PROG
(Magma) [(n^3 - n^2)*3^n: n in [1..25]]; // Vincenzo Librandi, Feb 11 2013
CROSSREFS
Sequence in context: A110693 A104671 A323549 * A281371 A090408 A268635
KEYWORD
nonn,easy
AUTHOR
Mohammad K. Azarian, Apr 30 2007
EXTENSIONS
Offset corrected by Mohammad K. Azarian, Nov 20 2008
STATUS
approved

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Last modified March 28 16:05 EDT 2024. Contains 371254 sequences. (Running on oeis4.)