A078203 Numbers k such that A004154(k) + 1 is prime.

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

Offset: 1

Author

Cino Hilliard, Dec 23 2002

Keywords

• nonn
• base
• more

Crossrefs

Cf. A004154, A078154, A078190, A078305.

Programs

Mathematica

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}]

Extensions

Extended by Joshua Zucker, Robert G. Wilson v and Jason Earls, Dec 24 2002

a(13) from Don Reble, Jan 12 2006

a(14)-a(17) from Michael S. Branicky, Jul 23 2023