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 A048509 a(n) = T(4,n), array T given by A048505. 3
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS n-th difference of a(n), a(n-1), ..., a(0) is (25, 36, 49, 64, 81...). 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). 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 PROG (MAGMA) [(n^2+17*n+64) * 2^(n-2) - 15: n in [0..30]]; // Vincenzo Librandi, Sep 26 2011 (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 CROSSREFS Sequence in context: A325819 A138081 A118543 * A044213 A044594 A205998 Adjacent sequences:  A048506 A048507 A048508 * A048510 A048511 A048512 KEYWORD nonn,easy AUTHOR STATUS approved

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Last modified May 16 09:28 EDT 2021. Contains 343940 sequences. (Running on oeis4.)