A079154 Numbers k such that reverse(A004154(k)) - 1 is prime.

3, 4, 12, 30, 33, 1406

Offset

1,1

Comments

The values corresponding to a(1)-a(6) have been certified prime with Primo. a(7) > 15000. - Giovanni Resta, Feb 20 2013

a(7) > 40000. - Michael S. Branicky, Jan 05 2025

Links

Table of n, a(n) for n=1..6.

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, 1, 800}]

Crossrefs

Cf. A078305, A004154.

Sequence in context: A287594 A296271 A000208 * A101716 A360992 A217477

Adjacent sequences: A079151 A079152 A079153 * A079155 A079156 A079157

Keyword

base,more,nonn

Author

Jason Earls and Robert G. Wilson v, Dec 27 2002

Extensions

a(6) from Giovanni Resta, Feb 20 2013

Status

approved