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 A180325 #10 Mar 30 2012 18:35:54
%S A180325 1,6,9,31,16,18,40,89
%N A180325 a(n) = k is the smallest number such that n is the number of distinct primes dividing k! + 1.
%C A180325 A greedy inverse to A066856. - R. J. Mathar, Jan 21 2011
%e A180325 a(6) = 18 because the 6 distinct primes dividing 18! + 1 = 6402373705728001
%e A180325 are {19, 23, 29, 61, 67, 123610951}.
%p A180325 with(numtheory):for n from 1 to 7 do:ind:=0:for k from 1 to 50 while(ind=0)
%p A180325 do: x:=k!+1:y:=nops(factorset(x)):if y=n then ind:=1:printf(`%d, `,k):else fi:od:
%p A180325 od:
%Y A180325 Cf. A038507.
%K A180325 nonn,hard
%O A180325 1,2
%A A180325 _Michel Lagneau_, Jan 18 2011