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 A130862 #31 Jul 04 2025 18:40:48
%S A130862 0,30,85,171,294,460,675,945,1276,1674,2145,2695,3330,4056,4879,5805,
%T A130862 6840,7990,9261,10659,12190,13860,15675,17641,19764,22050,24505,27135,
%U A130862 29946,32944,36135,39525,43120,46926,50949,55195,59670,64380,69331,74529,79980,85690,91665,97911,104434,111240,118335,125725,133416,141414
%N A130862 a(n) = (n-1)*(n+2)*(2*n+11)/2.
%H A130862 Vincenzo Librandi, <a href="/A130862/b130862.txt">Table of n, a(n) for n = 1..1000</a>
%H A130862 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1).
%F A130862 a(n) = (5/2)*(n+2)*(n+3)*(Sum_{j=1..n} Sum_{m=1..j} Sum_{k=1..m} (k^2-1))/(Sum_{j=1..n} Sum_{m=1..j} Sum_{k=1..m} k) = (5/2)*(n+2)*(n+3)*A130857(n)/A000332(n+3).
%F A130862 G.f.: x^2*(30-35*x+11*x^2)/(-1+x)^4. - _R. J. Mathar_, Nov 14 2007
%F A130862 a(n) = 4*a(n-1) - 6*a(n-2) + 4*a(n-3) - a(n-4); a(0)=0, a(1)=30, a(2)=85, a(3)=171. - _Harvey P. Dale_, May 01 2011
%t A130862 Rest[CoefficientList[Series[x^2(30-35x+11x^2)/(-1+x)^4,{x,0,30}],x]] (* or *) LinearRecurrence[{4,-6,4,-1},{0,30,85,171},30] (* _Harvey P. Dale_, May 01 2011 *)
%o A130862 (Magma) [(n-1)*(n+2)*(2*n+11)/2: n in [1..50]]; // _Vincenzo Librandi_, May 02 2011
%o A130862 (PARI) a(n)=(2*n^3 + 13*n^2 + 7*n - 22)/2 \\ _Charles R Greathouse IV_, May 02 2011
%Y A130862 Cf. A055998.
%K A130862 nonn,easy
%O A130862 1,2
%A A130862 _Roger L. Bagula_, Jul 22 2007
%E A130862 Edited by _N. J. A. Sloane_, May 01 2011