OFFSET
0,1
LINKS
Sean A. Irvine, Table of n, a(n) for n = 0..50
EXAMPLE
a(1) = 2 because 19, 17, 13 and 11 are all prime.
MATHEMATICA
Do[k = 1; While[ !PrimeQ[k*10^n - 1] || !PrimeQ[k*10^n - 3] || !PrimeQ[k*10^n - 7] || !PrimeQ[k*10^n - 9], k++ ]; Print[k], {n, 0, 35} ] (* Robert G. Wilson v *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Don Reble, Oct 17 2001
STATUS
approved