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 A090189 #6 Oct 12 2013 15:14:06
%S A090189 3,2,1,1,1,1,2,1,3,5,2,4,6,3,5,7,26,5,7,11,10,1,1,1,11,5,3,8,3,20,14,
%T A090189 4,2,39,1,16,4,6,3,56,8,7,17,14,4,21,7,13,13,22,30,10,22,6,2,43,3,17,
%U A090189 26,21,32,10,28,30,15,28,22,74,23,33,11,8,1,4,3,5,2,29,3,68,36,14,1,133,4
%N A090189 Least k such that k*p(n)#-p(n+1) is prime, where p(i)# denotes the i-th primorial and p(i) denotes the i-th prime.
%C A090189 k*p(n)#-p(n+1) is the greatest prime < k*p(n)#-p(n+1)-1 and if k*p(n)#-p(n+1)-1 is not prime it is the greatest prime < k*p(n)#-p(n+1) P is given in one other sequence
%e A090189 1*2*3*5*7*11*13-17=30013, 1*p(6)#-p(7)=30013, 1 is the least k for n=6
%e A090189 30013 is prime
%e A090189 a(7)=2 since 2*17#-19 = 1021001 is prime.
%o A090189 (PARI) primorial(n) = prod(i=1,primepi(n),prime(i)) A090189(n) = {local(k,a,b);k=1;a=primorial(prime(n));b=prime(n+1);while(!isprime(a*k-b),k++);k}
%K A090189 base,nonn
%O A090189 1,1
%A A090189 _Pierre CAMI_, Jan 21 2004
%E A090189 a(7) corrected by _Michael B. Porter_, Jan 29 2010