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 A268608 #6 Feb 13 2016 03:57:11 %S A268608 5,7,19,23,41,163,67,257,83,109,43,359,293,647,277,1567,983,419,1723, %T A268608 83,103,3089,719,733,1723,457,331,2729,3389,1123,863,1123,1871,6211, %U A268608 19717,5323,5749,419,887,811,617,2851,2531,5023,6883,6661,2879,16433,19471 %N A268608 a(n) is the least m > 1 such that (prime(n)#)^n - m is prime. %C A268608 Here prime(n)# denotes the primorial A002110(n), i.e., the product of the first n primes. a(1) is not defined (there are no primes less than 2). %C A268608 The definition is similar to Lesser Fortunate numbers (A055211) - but here primorials A002110(n) are raised to the n-th power. %C A268608 Similar to Fortunate numbers (A005235) and Lesser Fortunate numbers (A055211), the first fifty terms are all prime. (Cf. A263925 where the 6th term is composite.) %e A268608 a(2)=5 because m=5 is the least m > 1 such that A002110(2)^2 - m is prime. %o A268608 (PARI) a(n)=my(s=prod(i=1, n, prime(i))^n); s-precprime(s-2) %Y A268608 Cf. A002110, A005235, A055211, A264050, A263925, A268607. %K A268608 nonn %O A268608 2,1 %A A268608 _Alexei Kourbatov_, Feb 08 2016