OFFSET
1,2
COMMENTS
All terms except 1 are even.
Includes p-1 if p is a prime such that 10*p-9 is prime.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(5) = 12 is a term because 12 = 4*3 where both 43 and 4+3=7 are prime.
MAPLE
filter:= proc(m) local d, e;
for d in numtheory:-divisors(m) do
e:= m/d;
if isprime(d*10^(1+ilog10(e))+e) and isprime(d+e) then return true fi
od;
false
end proc:
select(filter, [$1..1000]);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. M. Bergot and Robert Israel, Apr 26 2021
STATUS
approved