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 A078203 #17 Jul 23 2023 20:16:51
%S A078203 1,2,3,5,6,14,15,24,74,191,222,276,2200,3041,3701,4324,6201
%N A078203 Numbers k such that A004154(k) + 1 is prime.
%t A078203 f[n_] := n!/10^Sum[ Floor[n/5^k], {k, 1, Log[10, n] + 1}]; Do[ If[ PrimeQ[ f[n] + 1], Print[n]], {n, 1, 850}]
%Y A078203 Cf. A004154, A078154, A078190, A078305.
%K A078203 nonn,base,more
%O A078203 1,2
%A A078203 _Cino Hilliard_, Dec 23 2002
%E A078203 Extended by _Joshua Zucker_, _Robert G. Wilson v_ and _Jason Earls_, Dec 24 2002
%E A078203 a(13) from _Don Reble_, Jan 12 2006
%E A078203 a(14)-a(17) from _Michael S. Branicky_, Jul 23 2023