OFFSET
1,1
COMMENTS
If p, p+2 and 3*p-2 are prime then 2*p is a term.
Is 12 the only term not of this form?
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
a(4) = 22 is a term because A238525(22) = 9 and 22-9 = 13 and 22+9 = 31 are prime.
MAPLE
filter:= proc(n) local t, s, r;
if isprime(n) then return false fi;
s:= add(t[1]*t[2], t=ifactors(n)[2]);
r:= n mod s;
isprime(n+r) and isprime(n-r);
end proc:
select(filter, [$4..10^5]);
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, Mar 17 2021
STATUS
approved