|
%I #9 Aug 05 2019 07:36:10
%S 0,-1,3,12,26,45,69,98,132,171,215,264,318,377,441,510,584,663,747,
%T 836,930,1029,1133,1242,1356,1475,1599,1728,1862,2001,2145,2294,2448,
%U 2607,2771,2940,3114,3293,3477,3666,3860,4059,4263,4472,4686,4905,5129,5358,5592
%N a(n) = (1/2)*n*(5*n - 7); row 5 of A326728.
%H Colin Barker, <a href="/A326725/b326725.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1).
%F From _Colin Barker_, Aug 04 2019: (Start)
%F G.f.: -x*(1 - 6*x) / (1 - x)^3.
%F a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>2.
%F (End)
%p a := n -> (1/2)*n*(5*n - 7): seq(a(n), n=0..48);
%o (PARI) concat(0, Vec(-x*(1 - 6*x) / (1 - x)^3 + O(x^40))) \\ _Colin Barker_, Aug 04 2019
%Y Cf. A326728.
%K sign,easy
%O 0,3
%A _Peter Luschny_, Aug 04 2019
|
