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 A279098 #10 Mar 29 2017 19:43:30
%S A279098 1,2,4,8,11,17,18,21,25,32,34,35,39,40,42,47,48,58,63,65,66,67,69,90,
%T A279098 91,97,105,110,122,140,144,151,152,162,166,168,173,174,175,179,180,
%U A279098 186,205,207,208,210,211,218,233,243,249,256,261,262,297,308,316,318
%N A279098 Numbers k such that prime(k) divides primorial(j) + 1 for exactly one integer j.
%C A279098 As used here, "primorial(j)" refers to the product of the first j primes, i.e., A002110(j).
%C A279098 Primorial(j) + 1 is the j-th Euclid number, A006862(j).
%H A279098 Giovanni Resta, <a href="/A279098/b279098.txt">Table of n, a(n) for n = 1..10000</a>
%e A279098 59 is not in this sequence because both primorial(7) + 1 = 510511 and primorial(17) + 1 = 1922760350154212639071 are divisible by prime(59) = 277.
%t A279098 np[1]=1; np[n_] := Block[{c=0, p=Prime[n], trg, x=1}, trg = p-1; Do[x = Mod[x Prime[k], p]; If[trg == x, c++], {k, n-1}]; c]; Select[Range[262], np[#] == 1 &] (* _Giovanni Resta_, Mar 29 2017 *)
%Y A279098 Subsequence of A279097 (which also includes numbers k such that prime(k) divides primorial(j) + 1 for more than one integer j).
%Y A279098 Cf. A000040, A002110, A006862, A113165, A279099, A283928.
%K A279098 nonn
%O A279098 1,2
%A A279098 _Jon E. Schoenfield_, Mar 24 2017