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 A073828 #9 Mar 30 2012 17:36:39 %S A073828 2,2,3,13,125411328001, %T A073828 69113789582492712943486800506462734562847413501952000000000000001 %N A073828 Primes of the form 1 + 0!*1!*2!*...*n! (subsequence of A019515). %C A073828 a(4) = 125411328001 and the 65-digit a(5) have been certified prime with Primo. Any additional terms are too big to include here. a(3) = 13 and a(4) have twin primes, 11 and 125411327999 (also certified prime with Primo). No other primes of the form 0!*1!*2!*...*n! - 1 exist for n < 108. %D A073828 Ryser, H. J. Combinatorial Mathematics. Buffalo, NY: Math. Assoc. Amer., p. 53, 1963. %H A073828 M. Fleuren, <a href="http://www.gallup.unm.edu/~smarandache/SmFactProd.txt">Smarandache Factorial Products</a>. %F A073828 a(k) = 1 + 0!*1!*2!*...*A073827(k)!. %e A073828 a(0) = 1 + 0! (0=A073827(0)) = 1 + 1 = 2. a(1) = 1 + 0!*1! (1=A073827(1)) = 1 + 1*1 = 2. a(4) = 1 + 0!*1!*2!*3!*4!*5!*6!*7! (7=A073827(4)) = 1 + 1*1*2*6*24*120*720*5040 = 125411328001 %o A073828 (PARI) pr=1; for(n=0,115, pr=pr*n!; if(isprime(pr+1), print1(pr+1,","))) %Y A073828 Cf. A073827 (corresponding n), A000178 (superfactorials), A019515 (supersequence: superfactorials + 1), A000142 (factorials). %K A073828 nonn %O A073828 1,1 %A A073828 _Rick L. Shepherd_, Aug 16 2002