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 A068239 #17 Dec 23 2014 19:50:34 %S A068239 1,123,4806,71410,583455,3232341,13675228,47502036,141991245, %T A068239 377162335,910842306,2033854758,4253012491,8411348505,15856955640, %U A068239 28673921896,49991146713,84387303171,138412872190,221253017370,345558093111,528471784093,792890261076 %N A068239 1/2 the number of colorings of a 3 X 3 square array with n colors. %H A068239 Alois P. Heinz, <a href="/A068239/b068239.txt">Table of n, a(n) for n = 2..1000</a> %F A068239 From _Alois P. Heinz_, Apr 27 2012: (Start) %F A068239 G.f.: x^2*(1199*x^7 +16567*x^6 +60099*x^5 +71075*x^4 +28765*x^3 +3621*x^2 +113*x+1) / (x-1)^10. %F A068239 a(n) = (79*n -323*n^2 +594*n^3 -648*n^4 +459*n^5 -216*n^6 +66*n^7 -12*n^8 +n^9) / 2. %F A068239 (End) %p A068239 a:= n-> (79+(-323+(594+(-648+(459+(-216+(66+(-12+n)*n)*n) *n)*n)*n)*n)*n) *n/2: %p A068239 seq(a(n), n=2..30); # _Alois P. Heinz_, Apr 27 2012 %Y A068239 Cf. A068239-A068305, A000332, A002417, A027441, A182368, A182406. %K A068239 nonn %O A068239 2,2 %A A068239 _R. H. Hardin_, Feb 24 2002