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A189737
a(1)=3, a(2)=3, a(n)=3*a(n-1) + 3*a(n-2).
12
3, 3, 18, 63, 243, 918, 3483, 13203, 50058, 189783, 719523, 2727918, 10342323, 39210723, 148659138, 563609583, 2136806163, 8101247238, 30714160203, 116446222323, 441481147578, 1673782109703, 6345789771843, 24058715644638, 91213516249443, 345816695682243
OFFSET
1,1
FORMULA
G.f.: 3*x*(1-2*x)/(1-3*x-3*x^2). - Bruno Berselli, May 24 2011
MATHEMATICA
LinearRecurrence[{3, 3}, {3, 3}, 40]
PROG
(Maxima) a[1]:3$ a[2]:3$ a[n]:=3*a[n-1]+3*a[n-2]$ makelist(a[n], n, 1, 26); /* Bruno Berselli, May 24 2011 */
KEYWORD
nonn,easy
AUTHOR
Harvey P. Dale, Apr 26 2011
STATUS
approved