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A113436
First row of A113435.
2
1, 2, 7, 26, 98, 371, 1406, 5329, 20196, 76532, 289997, 1098826, 4163483, 15775426, 59772826, 226477879, 858118966, 3251390237, 12319431012, 46677994276, 176861668393, 670124115506, 2539082288671, 9620514646154, 36451871795186
OFFSET
0,2
FORMULA
a(n) = A113435(3*n).
a(n) = 7*a(n-1) - 15*a(n-2) + 11*a(n-3) - a(n-4).
G.f.: (1 -5*x +8*x^2 -4*x^3)/(1 -7*x +15*x^2 -11*x^3 +x^4).
MATHEMATICA
CoefficientList[Series[(1 - 5*x + 8*x^2 - 4*x^3)/(1 - 7*x + 15*x^2 - 11*x^3 + x^4), {x, 0, 50}], x] (* or *) LinearRecurrence[{7, -15, 11, -1}, {1, 2, 7, 26}, 50] (* G. C. Greubel, Mar 10 2017 *)
PROG
(PARI) my(x='x+ O(x^50)); Vec((1 -5*x +8*x^2 -4*x^3)/(1 -7*x +15*x^2 -11*x^3 +x^4)) \\ G. C. Greubel, Mar 10 2017
CROSSREFS
Cf. A113435.
Sequence in context: A278351 A001075 A293210 * A126223 A369231 A369489
KEYWORD
nonn,easy
AUTHOR
Floor van Lamoen, Nov 04 2005
STATUS
approved