A091631 Next prime associated with A091628.

29, 227, 2237, 22229, 222247, 2222239, 22222253, 222222227, 2222222243, 22222222273, 222222222301, 2222222222243, 22222222222229, 222222222222227, 2222222222222281, 22222222222222301, 222222222222222281

Offset: 1

Author

Enoch Haga, Jan 24 2004

Keywords

• base
• easy
• nonn

Comments

Sequence arising in Farideh Firoozbakht's solution to Prime Puzzle 251 - 23 is the only pointer prime (A089823) not containing the digit "1".

The monotonically increasing value of successive product of digits (A091629) strongly suggests that in successive n the digit 1 must be present.

Examples

			a(1) = nextprime(23+1) = 29.
		

Links

• Carlos Rivera's Prime Puzzles and Problems Connection, Puzzle 251, Pointer primes

Crossrefs

Cf. A007918, A089823, A091628, A091629, A091630, A091632.

Programs

PARI

a(n) = nextprime((10^(n+1) - 1)/9*2 + 2); \\ Michel Marcus, Mar 18 2018

Formula

a(n) = A007918(A091628(n)+1).

Extensions

Edited and extended by Ray Chandler, Feb 07 2004