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 A231018 #10 Aug 09 2019 02:13:06 %S A231018 1,1,1,5,7315048,4293861989,11387819007325752,4244193265542951705 %N A231018 a(n) = d(n)/p(n-1)# where d(n) > 0 is the common difference of the smallest p-term arithmetic progression of primes beginning with p = p(n) = n-th prime. %C A231018 d(n) is the least d > 0 such that p, p+d, p+2d, ..., p+(p-1)d are all prime with p = p(n), and p(n-1)# = A002110(n-1) is a primorial. %C A231018 d(n) is always a multiple of p(n-1)#. %C A231018 a(5) and a(6) are due to G. Loh in 1986, and a(7) to Phil Carmody in 2001. %C A231018 See A088430 and A231017 for more comments, references, links, and examples. %H A231018 <a href="/index/Pri#primes_AP">Index entries for sequences related to primes in arithmetic progressions</a> %F A231018 a(n) = A088430(n) / A002110(n) = (A231017(n) - prime(n)) / A002110(n). %e A231018 Prime(3) = 5 and 5, 11, 17, 23, 29 is the smallest 5-term AP beginning with 5, so a(3) = (11-5)/p(2)# = 6/2*3 = 1. %Y A231018 Cf. A002110, A088430, A231017. %K A231018 nonn,hard,more %O A231018 1,4 %A A231018 _Jonathan Sondow_, Nov 08 2013 %E A231018 a(8) due to Wojciech Izykowski in 2014 added by _Jonathan Sondow_, Aug 08 2019