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A166035
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a(n)= (3^n+6*(-4)^n)/7.
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6
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1, -3, 15, -51, 231, -843, 3615, -13731, 57111, -221883, 907215, -3569811, 14456391, -57294123, 230770815, -918300291, 3687550071, -14707153563, 58957754415, -235443597171, 942936650151, -3768259816203, 15083499618015
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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FORMULA
| a(0)= 1, a(1)= -3, a(n)= 12*a(n-2)-a(n-1) for n>1. a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*(-4)^k. G.f.: (1-2x)/(1+x-12x^2).
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PROG
| (PARI) a(n)= (3^n+6*(-4)^n)/7;
for(n=0, 33, print1(a(n), ", "));
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CROSSREFS
| Cf. A077925, A091004
Sequence in context: A165746 A118126 A192742 * A038192 A147618 A085480
Adjacent sequences: A166032 A166033 A166034 * A166036 A166037 A166038
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KEYWORD
| easy,sign
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AUTHOR
| Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Oct 05 2009
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EXTENSIONS
| Corrected a(5)
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