OFFSET
1,2
EXAMPLE
a(5) = 21 and the number 199921 is a prime.
MATHEMATICA
a[1] = 1; a[n_] := a[n] = Block[{k = 3, c = IntegerDigits @ Table[ a[i], {i, n - 1}]}, While[PrimeQ[k] || !PrimeQ[FromDigits @ Flatten @ Append[c, IntegerDigits[k]]], k += 2]; k]; Table[ a[n], {n, 61}] (* Robert G. Wilson v, Aug 05 2005 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Amarnath Murthy, Mar 26 2002
EXTENSIONS
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 31 2003
STATUS
approved