A078203 - OEIS

%I #17 Jul 23 2023 20:16:51

%S 1,2,3,5,6,14,15,24,74,191,222,276,2200,3041,3701,4324,6201

%N Numbers k such that A004154(k) + 1 is prime.

%t 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 Cf. A004154, A078154, A078190, A078305.

%K nonn,base,more

%O 1,2

%A _Cino Hilliard_, Dec 23 2002

%E Extended by _Joshua Zucker_, _Robert G. Wilson v_ and _Jason Earls_, Dec 24 2002

%E a(13) from _Don Reble_, Jan 12 2006

%E a(14)-a(17) from _Michael S. Branicky_, Jul 23 2023