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%I A048509 #21 Jul 08 2023 10:35:16
%S A048509 1,26,87,233,577,1377,3217,7409,16881,38129,85489,190449,421873,
%T A048509 929777,2039793,4456433,9699313,21037041,45481969,98041841,210763761,
%U A048509 451936241,966787057,2063597553,4395630577,9344909297,19830669297,42010148849,88852135921
%N A048509 a(n) = T(4,n), array T given by A048505.
%C A048509 n-th difference of a(n), a(n-1), ..., a(0) is (25, 36, 49, 64, 81...).
%H A048509 Vincenzo Librandi, <a href="/A048509/b048509.txt">Table of n, a(n) for n = 0..2000</a>
%H A048509 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (7,-18,20,-8).
%F A048509 a(n) = (n^2+17*n+64) * 2^(n-2) - 15. - _Ralf Stephan_, Feb 05 2004
%F A048509 a(n) = 7*a(n-1)-18*a(n-2)+20*a(n-3)-8*a(n-4). - _Colin Barker_, Mar 04 2015
%F A048509 G.f.: (72*x^3-77*x^2+19*x+1) / ((x-1)*(2*x-1)^3). - _Colin Barker_, Mar 04 2015
%t A048509 LinearRecurrence[{7,-18,20,-8},{1,26,87,233},30] (* _Harvey P. Dale_, Jul 08 2023 *)
%o A048509 (Magma) [(n^2+17*n+64) * 2^(n-2) - 15: n in [0..30]]; // _Vincenzo Librandi_, Sep 26 2011
%o A048509 (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
%K A048509 nonn,easy
%O A048509 0,2
%A A048509 _Clark Kimberling_

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