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

1,1

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.

Links

Giovanni Resta, Table of n, a(n) for n = 1..59 (terms < 10^19)

Carlos Rivera and Joseph L. Pe, Pointer primes.

Example

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.

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}]

Crossrefs

Cf. A089823, A125841, A127836.

Sequence in context: A105310 A200072 A261264 * A069984 A358420 A104285

Adjacent sequences: A125837 A125838 A125839 * A125841 A125842 A125843

Keyword

hard,base,nonn

Author

Farideh Firoozbakht, Feb 02 2007

Extensions

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

Status

approved