A238856 Number of digits of the largest right-truncatable reversible prime in base n.

0, 3, 3, 4, 3, 4, 5, 4, 4, 6, 4, 6, 6, 6, 6, 5, 4, 7, 6, 7, 5, 6, 5, 8, 6, 6, 6, 6, 7, 7, 6, 6, 8, 6, 8, 7, 8, 8, 7, 8, 7, 8, 8, 8, 8, 7, 7, 9, 9, 8, 7, 8, 10, 10, 9, 8, 6, 9, 8, 7, 9, 9, 9, 9, 11, 8, 7, 9, 10, 9, 10, 9, 9, 11, 10, 10, 9, 9, 8, 9, 9, 8, 10, 10, 10, 9, 9, 9, 10, 11

Offset: 2

Author

Stanislav Sykora, Mar 13 2014

Keywords

• nonn
• base
• hard

Comments

For definitions and more comments, see A238854 and A238850. A weak conjecture: this sequence might be bounded.

Examples

			a(16) = 6 because the largest truncatable reversible prime in base 16 has 6 hexadecimal digits (see A238851).
		

Links

• Stanislav Sykora, Table of n, a(n) for n = 2..390
• Stanislav Sykora, PARI/GP scripts for genetic threads, with code and comments.

Crossrefs

Cf. Full in base 10: A238850, 16: A238851, 100: A238852, 256: A238853.

Cf. In base n: A238854 (largest), A238855 (totals), A238857 (m-digit counts).

Cf. A007500, A023107, A024770, A237600, A237601, A237602.

Programs

PARI

See the link.