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 A341805 #11 Mar 03 2021 22:05:06 %S A341805 0,2,4,9823712 %N A341805 Numbers k such that (product of first k primes)-1 is divisible by the (k+1)-th prime. %F A341805 a(n) = A000720(A341804(n)) - 1. %e A341805 4 is a member because 2*3*5*7-1 (product of first 4 primes, minus one) is divisible by the 5th prime, 11. %e A341805 9823712 is a member because 2*3*5*...*176078267-1 is divisible by 176078293, where 176078267 is the 9823712th prime. %o A341805 (PARI) isok(k) = ((vecprod(primes(k)) - 1) % prime(k+1)) == 0; \\ _Michel Marcus_, Mar 03 2021 %Y A341805 Cf. A079276, A081618, A338543, A341804, A341812. %K A341805 nonn,hard,more %O A341805 1,2 %A A341805 _Jeppe Stig Nielsen_, Feb 20 2021