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 A233745 #9 Jul 16 2015 22:47:02
%S A233745 1,2,5,7,8,10,11,13,14,16,17,18,20,21,22,23,24,25,26,27,28,29,32,33,
%T A233745 34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,
%U A233745 57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76
%N A233745 a(n) = smallest number > a(n-1) such that a(1)*a(2)*...*a(n) - 1 is nonprime.
%C A233745 The numbers 3, 4, 6, 8, 9, 12, 15, 19, 30, 31, 81, 152, 390, ... are not in the sequence.
%e A233745 1-1 = 0, 1*2-1 = 1, 1*2*5-1 = 9, 1*2*5*7 - 1 = 69, etc. are nonprimes.
%t A233745 seq={1}; Do[n=Last[seq]+1; While[PrimeQ[n Times@@seq-1], n++]; AppendTo[ seq, n]; , {60}]; seq
%Y A233745 Cf. A051957, A233746.
%K A233745 nonn
%O A233745 1,2
%A A233745 _Michel Lagneau_, Dec 15 2013