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 A081711 #15 May 07 2025 08:29:28 %S A081711 2,3,4,5,8,17,23,26,35,47,82,100,147,183,271,492,708,1116,1538,2491, %T A081711 4207,4468,8147 %N A081711 Numbers k such that k! + k# - 1 is prime, where k# is the primorial function A034386(k). %C A081711 Some of the larger entries may only correspond to probable primes. %H A081711 Mike Oakes, <a href="http://groups.yahoo.com/group/primenumbers/message/12028">Primo-factorials</a>. %H A081711 Mike Oakes, <a href="/A081710/a081710.txt">Primo-factorials</a>, message 12028 in primenumbers Yahoo group, Apr 3, 2003. [Cached copy] %e A081711 a(1)=2 because 2!+2#-1=3 is prime %Y A081711 Cf. A034386, A081710, A081712, A081713. %K A081711 nonn,more,hard %O A081711 1,1 %A A081711 _Mike Oakes_, Apr 04 2003 %E A081711 Offset and ordering corrected by _Sean A. Irvine_, Sep 18 2023 %E A081711 a(23) from _Michael S. Branicky_, May 06 2025