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 A244502 #21 Oct 11 2017 05:11:26
%S A244502 33,378,2190,9110,30300,85563,213293,482085,1006950,1971185,3655053,
%T A244502 6472533,11017505,18120840,28919970,44942618,68206473,101336700,
%U A244502 147703280,211580280,298329258,414609113,568614795,770347395,1031918240,1367889723,1795655703,2335864415
%N A244502 Number of ways to place 4 points on an n X n X n triangular grid so that no pair of them has distance sqrt(3).
%C A244502 sqrt(3) is the second closest (Euclidean) distance for a pair of points in a triangular grid. For illustration see A244500.
%H A244502 Heinrich Ludwig, <a href="/A244502/b244502.txt">Table of n, a(n) for n = 4..1000</a>
%H A244502 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (9,-36,84,-126,126,-84,36,-9,1).
%F A244502 a(n) = 1/384*n^8 + 1/96*n^7 - 13/64*n^6 + 5/48*n^5 + 875/128*n^4 - 2543/96*n^3 - 4141/96*n^2 + 3759/8*n - 837, for n >= 5.
%F A244502 G.f.: x^4*(10*x^9 - 30*x^8 + 130*x^6 - 333*x^5 + 444*x^4 - 236*x^3 + 24*x^2 - 81*x - 33) / (x - 1)^9. - _Colin Barker_, Jun 29 2014
%p A244502 A244502:=n->`if`(n=4,33,1/384*n^8 + 1/96*n^7 - 13/64*n^6 + 5/48*n^5 + 875/128*n^4 - 2543/96*n^3 - 4141/96*n^2 + 3759/8*n - 837); seq(A244502(n), n=4..30); # _Wesley Ivan Hurt_, Jun 30 2014
%t A244502 CoefficientList[Series[(10*x^9 - 30*x^8 + 130*x^6 - 333*x^5 + 444*x^4 - 236*x^3 + 24*x^2 - 81*x - 33)/(x - 1)^9, {x, 0, 30}], x] (* _Wesley Ivan Hurt_, Jun 30 2014 *)
%o A244502 (PARI) Vec(x^4*(10*x^9-30*x^8+130*x^6-333*x^5+444*x^4-236*x^3+24*x^2-81*x-33)/(x-1)^9 + O(x^100)) \\ _Colin Barker_, Jun 29 2014
%Y A244502 Cf. A086274, A244500, A244501, A244503.
%K A244502 nonn,easy
%O A244502 4,1
%A A244502 _Heinrich Ludwig_, Jun 29 2014