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 A057017 #6 Aug 12 2024 13:08:32
%S A057017 1,2,3,9,12,22,26,30,34,51,54,100,125,155,168,173,220,401,494,2161,
%T A057017 2539,2866,7625,9644,12099,13470,16078,18587,30075,37067
%N A057017 Numbers k such that the product of the first k composite numbers minus 1 is a prime.
%e A057017 a(3) = 3 because 4*6*8-1 = 191 which is prime.
%t A057017 Composite[ n_Integer ] := (k = n + PrimePi[ n ] + 1; While[ k - PrimePi[ k ] - 1 != n, k++ ]; k); Do[ m = n; If[ PrimeQ[ Product[ Composite[ k ], {k, 1, n} ] - 1 ], Print[ n ] ], {n, 1, 1980} ]
%Y A057017 Cf. A049421, A053982, A140293.
%K A057017 nonn
%O A057017 1,2
%A A057017 _Robert G. Wilson v_, Apr 21 2001
%E A057017 More terms via A049421 from _Jeppe Stig Nielsen_, Aug 12 2024