OFFSET
0,1
EXAMPLE
31, 631, 9631, 129631, etc. are primes.
a(10) = 231 because 2311626642393027129631 is prime.
MAPLE
ds:=proc(s) local j: RETURN(add(s[j]*10^(j-1), j=1..nops(s))): end: a:=[]: k1:=1: for n from 1 to 50 do for k from k1 do m:=ds([1, seq(op(convert(a[i], base, 10)), i=1..nops(a)), op(convert(3*k, base, 10))]): if isprime(m) then k1:=k+1: a:=[op(a), 3*k]: break fi od od: op(a); # C. Ronaldo
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 22 2003
EXTENSIONS
More terms from Jim Nastos, Jan 31 2004
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 26 2004
STATUS
approved