A091631 Next prime associated with A091628.

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

Offset

1,1

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.

Links

Table of n, a(n) for n=1..17.

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

Formula

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

Example

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

Prog

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

Crossrefs

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

Sequence in context: A146224 A287306 A142066 * A244767 A146421 A093401

Adjacent sequences: A091628 A091629 A091630 * A091632 A091633 A091634

Keyword

base,easy,nonn

Author

Enoch Haga, Jan 24 2004

Extensions

Edited and extended by Ray Chandler, Feb 07 2004

Status

approved