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 A069268 #9 Apr 06 2017 09:13:21
%S A069268 1,1,6,2,15,3,28,36,45,5,66,6,91,105,120,8,153,9,190,210,231,11,276,
%T A069268 300,325,351,378,14,435,15,496,528,561,595,630,18,703,741,780,20,861,
%U A069268 21,946,990,1035,23,1128,1176,1225,1275,1326
%N A069268 Greatest common divisor of n! and n*(n+1)/2.
%H A069268 Paolo P. Lava, <a href="/A069268/b069268.txt">Table of n, a(n) for n = 1..10000</a>
%F A069268 a(n) = if n>1 and n+1 is prime then n/2 else n*(n+1)/2.
%t A069268 Table[GCD[n!,(n(n+1))/2],{n,60}] (* _Harvey P. Dale_, Oct 14 2013 *)
%Y A069268 Cf. A000142, A000217, A000040.
%Y A069268 Cf. A090585, A090586.
%K A069268 nonn
%O A069268 1,3
%A A069268 _Reinhard Zumkeller_, Apr 14 2002