A078394 Numbers k such that reverse(A004154(k)) + 1 is prime.

0, 1, 2, 3, 4, 39, 256

Offset: 1

Author

Jason Earls, Dec 24 2002

Keywords

• base
• more
• nonn

Comments

Some of the larger entries may only correspond to probable primes.

a(8) > 25000. - Michael S. Branicky, Aug 20 2025

Crossrefs

Cf. A078203, A004154.

Programs

Mathematica

f[n_] := n!/10^Sum[Floor[n/5^k], {k, 1, Log[10, n] + 1}]; Do[ If[ PrimeQ[ FromDigits[ Reverse[ IntegerDigits[ f[n]]]] + 1], Print[n]], {n, 0, 800}]

Extensions

a(1) = 0 inserted by Michael S. Branicky, Aug 20 2025