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 A143772 #11 Aug 02 2019 22:59:24
%S A143772 1,1,3,2,1,1,3,8,1,1,3,2,1,1,2,3,4,1,1,3,2,1,12,1,3,8,1,1,3,2,1,1,2,3,
%T A143772 4,1,1,8,3,2,1,1,3,8,1,6,1,3,2,1,1,3,4,1,6,1,3,2,1,1,2,3,8,1,1,4,3,2,
%U A143772 1,24,1,3,4,1,1,3,2,1,1,3,8,1,1,4,3,2,1,24,1,2,3,4,1,6,1,3,2,1,1,2,3,8,1,1,3
%N A143772 If m is the n-th composite, then a(n) = gcd(k + m/k), where k is over all divisors of m.
%C A143772 Conjecture: All even numbers are terms and the only odd numbers which are terms are 1 and 3. - _Robert G. Wilson v_, Sep 08 2008
%e A143772 For n=11, 20 is the 11th composite. So we have a(11) = gcd(1+20, 2+10, 4+5, 5+4, 10+2, 20+1) = 3.
%t A143772 Composite[n_Integer] := FixedPoint[n + PrimePi@# + 1 &, n + PrimePi@n + 1]; f[n_] := Block[{m = Composite@n}, Last@ FoldList[ GCD, m!, # + m/# & /@ Divisors@m]]; Array[f, 105] (* _Robert G. Wilson v_, Sep 08 2008 *)
%Y A143772 Cf. A143771.
%K A143772 nonn
%O A143772 1,3
%A A143772 _Leroy Quet_, Aug 31 2008
%E A143772 More terms from _Robert G. Wilson v_, Sep 08 2008