OFFSET
1,1
COMMENTS
Numbers k such that the sums of primes <= k and of nonprimes <= k are both prime (not necessarily distinct).
All terms == 0 or 3 (mod 4).
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
MAPLE
sp:= proc(n) option remember; if isprime(n) then procname(n-1)+[0, n] else procname(n-1)+[n, 0] fi end proc:
sp(1):= [1, 0]:
filter:= proc(n) andmap(isprime, sp(n)) end proc:
select(filter, [$1..10000]);
CROSSREFS
KEYWORD
nonn
AUTHOR
J. M. Bergot and Robert Israel, May 24 2021
STATUS
approved