OFFSET
1,1
LINKS
Robert Israel, Table of n, a(n) for n = 1..990
MAPLE
A:= proc(n) local j, x, t;
x:= (10^n-1)/3;
for t from 1 to 2^n do
if isprime(x) then return x fi;
j:= padic:-ordp(t, 2);
x:= x - (x mod 10^j) + (7 * 10^j-1)/3;
od:
0
end proc:
seq(A(n), n=1..100); # Robert Israel, Apr 22 2016
MATHEMATICA
Table[SelectFirst[FromDigits/@(Join[#, {3}]&/@Tuples[{3, 5}, n]), PrimeQ], {n, 0, 20}](* The program uses the SelectFirst function from Mathematica version 10 *) (* Harvey P. Dale, Oct 07 2014 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Patrick De Geest, Jan 04 1999
STATUS
approved