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A016306
Expansion of 1/((1-2*x)*(1-6*x)*(1-9*x)).
1
1, 17, 205, 2165, 21421, 204437, 1909885, 17608805, 160998541, 1464103157, 13267627165, 119952839045, 1082840722861, 9765157542677, 88003964122045, 792740954558885, 7138900255858381, 64275492291826997
OFFSET
0,2
FORMULA
G.f.: 1/((1-2*x)*(1-6*x)*(1-9*x)).
From Vincenzo Librandi, Sep 01 2011: (Start)
a(n) = (2^n - 21*6^n + 27*9^n)/7.
a(n) = 17*a(n-1) - 84*a(n-2) + 108*a(n-3) for n > 2.
a(n) = 15*a(n-1) - 54*a(n-2) + 2^n. (End)
MATHEMATICA
CoefficientList[Series[1/((1-2x)(1-6x)(1-9x)), {x, 0, 30}], x] (* or *) LinearRecurrence[{17, -84, 108}, {1, 17, 205}, 30] (* Harvey P. Dale, Jan 19 2019 *)
PROG
(Magma) [(2^n-21*6^n+27*9^n)/7: n in [0..20]]; // Vincenzo Librandi, Sep 01 2011
CROSSREFS
Sequence in context: A017897 A016311 A140961 * A021092 A219124 A246989
KEYWORD
nonn,easy
STATUS
approved