A048509 a(n) = T(4,n), array T given by A048505.
1, 26, 87, 233, 577, 1377, 3217, 7409, 16881, 38129, 85489, 190449, 421873, 929777, 2039793, 4456433, 9699313, 21037041, 45481969, 98041841, 210763761, 451936241, 966787057, 2063597553, 4395630577, 9344909297, 19830669297, 42010148849, 88852135921
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..2000
- Index entries for linear recurrences with constant coefficients, signature (7,-18,20,-8).
Programs
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Magma
[(n^2+17*n+64) * 2^(n-2) - 15: n in [0..30]]; // Vincenzo Librandi, Sep 26 2011
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Mathematica
LinearRecurrence[{7,-18,20,-8},{1,26,87,233},30] (* Harvey P. Dale, Jul 08 2023 *) -
PARI
Vec((72*x^3-77*x^2+19*x+1)/((x-1)*(2*x-1)^3) + O(x^100)) \\ Colin Barker, Mar 04 2015
Formula
a(n) = (n^2+17*n+64) * 2^(n-2) - 15. - Ralf Stephan, Feb 05 2004
a(n) = 7*a(n-1)-18*a(n-2)+20*a(n-3)-8*a(n-4). - Colin Barker, Mar 04 2015
G.f.: (72*x^3-77*x^2+19*x+1) / ((x-1)*(2*x-1)^3). - Colin Barker, Mar 04 2015
Comments