This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A326725 #13 Dec 24 2024 22:12:30 %S A326725 0,-1,3,12,26,45,69,98,132,171,215,264,318,377,441,510,584,663,747, %T A326725 836,930,1029,1133,1242,1356,1475,1599,1728,1862,2001,2145,2294,2448, %U A326725 2607,2771,2940,3114,3293,3477,3666,3860,4059,4263,4472,4686,4905,5129,5358,5592 %N A326725 a(n) = (1/2)*n*(5*n - 7); row 5 of A326728. %H A326725 Colin Barker, <a href="/A326725/b326725.txt">Table of n, a(n) for n = 0..1000</a> %H A326725 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (3,-3,1). %F A326725 From _Colin Barker_, Aug 04 2019: (Start) %F A326725 G.f.: -x*(1 - 6*x)/(1 - x)^3. %F A326725 a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n > 2. (End) %F A326725 E.g.f.: exp(x)*x*(5*x - 2)/2. - _Elmo R. Oliveira_, Dec 24 2024 %p A326725 a := n -> (1/2)*n*(5*n - 7): seq(a(n), n=0..48); %o A326725 (PARI) concat(0, Vec(-x*(1 - 6*x) / (1 - x)^3 + O(x^40))) \\ _Colin Barker_, Aug 04 2019 %Y A326725 Cf. A326728. %K A326725 sign,easy %O A326725 0,3 %A A326725 _Peter Luschny_, Aug 04 2019