OFFSET
1,1
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..2000
EXAMPLE
3 is in the sequence because 223 is prime.
67 is in the sequence because 2267 is prime.
111 is in the sequence because 22111 is prime.
MAPLE
a:= proc(n) local k; for k from 1 +`if`(n=1, 0, a(n-1))
while not isprime(parse(""||22||k)) do od; a(n):=k
end:
seq(a(n), n=1..100); # Alois P. Heinz, Jul 30 2014
MATHEMATICA
Select[Range[700], PrimeQ[22 10^IntegerLength[#] + #] &] (* Vincenzo Librandi, Jul 30 2014 *)
PROG
(Magma) [ n: n in [1..600] | IsPrime(Seqint(Intseq(n) cat [2, 2])) ]; // Klaus Brockhaus, Feb 03 2011
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Parthasarathy Nambi, Aug 24 2005
STATUS
approved