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A027001
a(n) = T(2*n, n+2), T given by A026998.
1
1, 26, 174, 743, 2552, 7784, 22193, 60882, 163430, 433495, 1142496, 3001056, 7869649, 20619098, 54001422, 141401879, 370224248, 969294632, 2537687585, 6643800690, 17393752166, 45537499111, 119218794624, 312118940928, 817138091617, 2139295405274
OFFSET
2,2
FORMULA
a(n-2) = 3*F(2n+10)-2*F(2n+9)-F(2n+8)-4n^3-26n^2-68n-75, F(n) = A000045(n). - Ralf Stephan, Feb 07 2004
From Colin Barker, Feb 18 2016: (Start)
a(n) = (2^(-1-n)*(-11*2^(1+n)+(11-5*sqrt(5))*(3-sqrt(5))^n+(3+sqrt(5))^n*(11+5*sqrt(5)))-12*n-2*n^2-4*n^3).
G.f.: x^2*(1+x)*(1+18*x-7*x^2) / ((1-x)^4*(1-3*x+x^2)).
(End)
MATHEMATICA
LinearRecurrence[{7, -19, 26, -19, 7, -1}, {1, 26, 174, 743, 2552, 7784}, 30] (* Vincenzo Librandi, Feb 19 2016 *)
PROG
(PARI) Vec(x^2*(1+x)*(1+18*x-7*x^2)/((1-x)^4*(1-3*x+x^2)) + O(x^40)) \\ Colin Barker, Feb 18 2016
(Magma) [3*Fibonacci(2*n+10)-2*Fibonacci(2*n+9)-Fibonacci(2*n+8)-4*n^3-26*n^2-68*n-75: n in [0..30]]; // Vincenzo Librandi, Feb 19 2016
CROSSREFS
Bisection of A027964.
Sequence in context: A321113 A126494 A374489 * A173893 A252936 A218083
KEYWORD
nonn,easy
STATUS
approved