OFFSET
1,1
COMMENTS
a(n) == 0 (mod 3) for n > 1.
a(n) <> 4 (mod 7) and a(n) <> 9 (mod 11) for n > 2 (where <> means "not equal"). - M. F. Hasler, Oct 15 2012
Terms a(13) onward do not exist as at least one of the corresponding concatenations is always divisible by 7. - Max Alekseyev, Oct 14 2012
EXAMPLE
a(1) = 2 since 211 is prime.
a(4) = 189 since 18911, 18913, 18917 and 18919 are all prime.
PROG
(PARI) A088266(n)=for(t=1, 9e9, for(k=1, n, isprime(t*10^((k+7)\4)+A088265(k))||next(2)); return(t)) \\ Only useful for n<9. - M. F. Hasler, Oct 15 2012
CROSSREFS
KEYWORD
base,nonn,fini,full
AUTHOR
Amarnath Murthy, Sep 28 2003
EXTENSIONS
More terms from David Wasserman, Jul 27 2005
a(10..12) from Don Reble, Oct 15 2012
a(10..12) confirmed by D. S. McNeil, Oct 16 2012
STATUS
approved