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 A110049 #9 Jan 03 2022 13:54:34 %S A110049 0,0,0,0,0,2,3,3,3,3,0,5,8,4,10,1,4,2,5,1,11,7,1,2,6,6,11,2,9,10,18,9, %T A110049 32,3,8,18,15,3,18,1,18,4,2,24,14,32,149,12,1,67,49,56,1,12,10,15,3,7, %U A110049 17,5 %N A110049 a(n) is the least j such that (prime(n)#)*3^j + 1 is prime, where prime(n)# is the n-th primorial. %t A110049 a[n_] := Module[{p = Product[Prime[i], {i, 1, n}], j = 0}, While[!PrimeQ[p * 3^j + 1], j++]; j]; Array[a, 100] (* _Amiram Eldar_, Sep 11 2021 *) %t A110049 Module[{j=0},While[!PrimeQ[# 3^j+1],j++];j]&/@FoldList[ Times,Prime[ Range[60]]] (* _Harvey P. Dale_, Jan 03 2022 *) %Y A110049 Cf. A002110. %K A110049 nonn %O A110049 1,6 %A A110049 _Pierre CAMI_, Sep 04 2005