OFFSET

1,1

COMMENTS

There are no more terms for m <= 34936. - Herman Jamke (hermanjamke(AT)fastmail.fm), Apr 29 2007

LINKS

EXAMPLE

a(1)= because 3*10^1-1 = 29 and 3*10^1+1 = 31 are primes.

a(2)= because 6*10^1-1 = 59 and 6*10^1+1 = 61 are primes.

a(3)= because 6*10^2-1 = 599 and 6*10^2+1 = 601 are primes.

a(4)= because 3*10^3-1 = 2999 and 3*10^3+1 = 3001 are primes.

a(5)= because 9*10^3-1 = 8999 and 9*10^3+1 = 9001 are primes.

a(6)= because 3*10^7-1 = 29999999 and 3*10^7+1 = 30000001 are primes.

MATHEMATICA

Select[FromDigits/@Flatten[Table[PadRight[{k}, n, 9], {k, {2, 5, 8}}, {n, 2, 10}], 1], AllTrue[ #+{0, 2}, PrimeQ]&]//Union (* Harvey P. Dale, May 14 2024 *)

CROSSREFS

KEYWORD

more,nonn

AUTHOR

Lekraj Beedassy, Dec 21 2006

EXTENSIONS

Edited by N. J. A. Sloane, Jan 01 2007

STATUS

approved