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 A119771 #21 Aug 31 2025 12:56:31
%S A119771 0,1,16,90,320,875,2016,4116,7680,13365,22000,34606,52416,76895,
%T A119771 109760,153000,208896,280041,369360,480130,616000,781011,979616,
%U A119771 1216700,1497600,1828125,2214576,2663766,3183040,3780295,4464000,5243216,6127616,7127505,8253840
%N A119771 Product of n^2 and n-th tetrahedral number: a(n) = n^3*(n+1)*(n+2)/6.
%C A119771 If n is divisible by 10, then a(n) is divisible by 1000.
%H A119771 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (6,-15,20,-15,6,-1).
%F A119771 From _Alois P. Heinz_, Feb 10 2023: (Start)
%F A119771 a(n) = Sum_{k=0..n} k^2 * A061579(n,k).
%F A119771 G.f.: x*(x+1)*(9*x+1)/(x-1)^6. (End)
%F A119771 From _Amiram Eldar_, Feb 13 2023: (Start)
%F A119771 Sum_{n>=1} 1/a(n) = 39/8 - 3*Pi^2/4 + 3*zeta(3).
%F A119771 Sum_{n>=1} (-1)^(n+1)/a(n) = 12*log(2) - 51/8 - 3*Pi^2/8 + 9*zeta(3)/4. (End)
%F A119771 E.g.f.: exp(x)*x*(6 + 42*x + 45*x^2 + 13*x^3 + x^4)/6. - _Stefano Spezia_, Aug 31 2025
%e A119771 a(25) = n^3*(n+1)*(n+2)/6 = 25^3*(25+1)*(25+2)/6 = 15625*26*27/6 = 15625*13*9 = 1828125.
%t A119771 a[n_] := n^3*(n+1)*(n+2)/6; Array[a, 35, 0] (* _Amiram Eldar_, Feb 13 2023 *)
%Y A119771 Cf. A000290, A000292, A061579.
%K A119771 easy,nonn,changed
%O A119771 0,3
%A A119771 Brandon Ang (xyz1236(AT)verizon.net), Jun 28 2006