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 A050494 #18 Jun 13 2015 00:50:02
%S A050494 1,10,52,192,570,1452,3300,6864,13299,24310,42328,70720,114036,178296,
%T A050494 271320,403104,586245,836418,1172908,1619200,2203630,2960100,3928860,
%U A050494 5157360,6701175,8625006,11003760,13923712,17483752,21796720,26990832,33211200,40621449
%N A050494 Partial sums of A051923.
%C A050494 If Y is a 3-subset of an n-set X then, for n>=9, a(n-9) is the number of 9-subsets of X having at least two elements in common with Y. - _Milan Janjic_, Nov 23 2007
%D A050494 A. H. Beiler, Recreations in the Theory of Numbers, Dover, N.Y., 1964, pp. 194-196.
%H A050494 <a href="/index/Rec#order_08">Index entries for linear recurrences with constant coefficients</a>, signature (8,-28,56,-70,56,-28,8,-1)
%F A050494 a(n)=C(n+6, 6)*(3n+7)/7.
%F A050494 G.f.: (1+2*x)/(1-x)^8.
%t A050494 Table[Binomial[n+6, 6]*(3*n+7)/7, {n, 0, 50}] (* _Vladimir Joseph Stephan Orlovsky_, Jan 27 2012 *)
%Y A050494 Cf. A051923.
%Y A050494 Cf. A093560 ((3, 1) Pascal, column m=7).
%K A050494 easy,nonn
%O A050494 0,2
%A A050494 _Barry E. Williams_, Dec 26 1999