OFFSET
1,1
COMMENTS
The number of digits of p that are not divisible by 3 is divisible by 3.
LINKS
Robert Israel, Table of n, a(n) for n = 1..250
EXAMPLE
MAPLE
filter:= proc(n) local t, x, d;
if not isprime(n) then return false fi;
d:= add(t^2, t=convert(n, base, 10));
x:= n+d;
if not isprime(x) then return false fi;
if not isprime(x+add(t^2, t=convert(x, base, 10))) then return false fi;
x:= n-d;
isprime(x) and isprime(x-add(t^2, t=convert(x, base, 10)))
end proc:
select(filter, [seq(i, i=3..3*10^7, 2)]);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Mar 31 2021
STATUS
approved