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 A109769 #7 Jul 23 2014 12:06:11
%S A109769 18,25,133,2107,4676,226037,4477739,827867201
%N A109769 Composite n such that binomial(7*n, n) == 7^n (mod n).
%C A109769 No other terms below 10^9.
%H A109769 Max Alekseyev, <a href="http://home.gwu.edu/~maxal/gpscripts/">PARI/GP scripts for various problems</a>
%e A109769 18 is a term because binomial(7*18, 18) = 2797093093529137508875, 7^18 = 1628413597910449 and 2797093093529137508875 mod 18 = 1628413597910449 mod 18 = 1.
%t A109769 Do[If[ !PrimeQ[n], If[Mod[Binomial[7*n, n], n] == Mod[7^n, n], Print[n]]], {n, 2, 20000}]
%Y A109769 Cf. A080469.
%K A109769 more,nonn
%O A109769 1,1
%A A109769 _Ryan Propper_, Aug 13 2005
%E A109769 226037 from _Max Alekseyev_, Sep 13 2009
%E A109769 Two more terms from _Max Alekseyev_, Nov 06 2009