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 A011931 #19 Jul 07 2025 18:49:18
%S A011931 0,0,0,0,1,5,17,40,80,144,240,377,565,817,1144,1560,2080,2720,3497,
%T A011931 4429,5537,6840,8360,10120,12144,14457,17085,20057,23400,27144,31320,
%U A011931 35960,41097,46765,53001,59840,67320,75480,84360,94001,104445,115737,127920,141040,155144,170280,186497,203845,222377,242144
%N A011931 a(n) = floor(n*(n-1)*(n-2)*(n-3)/21).
%H A011931 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (4,-6,4,-1,0,0,1,-4,6,-4,1).
%F A011931 a(n) = +4*a(n-1) -6*a(n-2) +4*a(n-3) -a(n-4) +a(n-7) -4*a(n-8) +6*a(n-9) -4*a(n-10) +a(n-11). - _R. J. Mathar_, Apr 15 2010
%t A011931 Table[Floor[n (n - 1) (n - 2) (n - 3)/21], {n, 0, 30}] (* _Wesley Ivan Hurt_, Jun 18 2022 *)
%o A011931 (Magma) [Floor(n*(n-1)*(n-2)*(n-3)/21) : n in [0..60]]; // _Wesley Ivan Hurt_, Jul 07 2025
%K A011931 nonn,easy
%O A011931 0,6
%A A011931 _N. J. A. Sloane_