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 A093173 #23 Mar 16 2015 01:39:57
%S A093173 7,47,383,10321919,51011754393599,
%T A093173 1130138339199322632554990773529330319359999999,
%U A093173 73562883979319395645666688474019139929848516028923903999999999,4208832729023498248022825567687608993477547383960134557368319999999999
%N A093173 Primes of the form (2^n * n!) - 1.
%C A093173 Primes resulting from serial multiplication of even numbers, minus 1.
%C A093173 For primes of the form 2^n*n! + 1, trivially a(1)=3, a(2) = 2^259*259! + 1 (593 digits). - _Ray Chandler_, Mar 27 2004
%H A093173 Charles R Greathouse IV, <a href="/A093173/b093173.txt">Table of n, a(n) for n = 1..12</a>
%F A093173 Starting with 2, multiply even numbers until the product, minus 1, equals a prime.
%F A093173 a(n) = A117141(n+1). - _Alexander Adamchuk_, Apr 18 2007
%e A093173 a(1) multiplies the first 2 terms, 2*4-1. a(3) multiplies first 4 terms, a(4) multiplies first 8 terms, a(5) multiplies first 13 terms in 12 multiplications.
%e A093173 a(2)=47, formed by 2*4*6 - 1 = 47.
%t A093173 lst={};Do[If[PrimeQ[p=(2^n*n!)-1],AppendTo[lst,p]],{n,5!}];lst (* _Vladimir Joseph Stephan Orlovsky_, Jan 28 2009 *)
%o A093173 (PARI) v=[];for(n=1,404,if(ispseudoprime(t=n!<<n-1),v=concat(v,t))) \\ _Charles R Greathouse IV_, Feb 14 2011
%Y A093173 Cf. A093154, A093155.
%Y A093173 Cf. A117141 (primes of the form n!! - 1).
%K A093173 nonn
%O A093173 1,1
%A A093173 _Enoch Haga_, Mar 27 2004
%E A093173 More terms from _Ray Chandler_, Mar 27 2004
%E A093173 a(8) from _Robert Price_, Mar 13 2015