A125840 Two-sided multiplicative pointer primes.

1123, 21911, 3116111, 11413111, 12111331, 14111311, 316111111, 1111131821, 11112119111, 11161211111, 111161111311, 111211231111, 1111112111191, 2111191111111, 11131211113111, 21111121126111, 31111127111111, 111211151611111, 111211222111123, 121132111712111

Offset: 1

Author

Farideh Firoozbakht, Feb 02 2007

Keywords

• hard
• base
• nonn

Comments

Following the definition of multiplicative pointer primes (A089823), I call a prime p a two-sided multiplicative pointer prime if previous_prime(p)=p-P and next_prime(p)=p+P where P is the product of the digits of p.

Examples

			11112119111 is in the sequence because previous_prime(11112119111)
= 11112119111 - 1*1*1*1*2*1*1*9*1*1*1 and next_prime(11112119111)
= 11112119111 + 1*1*1*1*2*1*1*9*1*1*1.
		

Links

• Giovanni Resta, Table of n, a(n) for n = 1..59 (terms < 10^19)
• Carlos Rivera and Joseph L. Pe, Pointer primes.

Crossrefs

Cf. A089823, A125841, A127836.

Programs

Mathematica

Do[p=Prime[m];P=Apply[Times,IntegerDigits[p]];If[Prime[m-1]== p-P&&Prime[m+1]==p+P,Print[p]],{m,2,140000000}]

Extensions

a(9)-a(20) from Donovan Johnson, Oct 21 2013