OFFSET
0,5
COMMENTS
First n > 1 with n != 0 (mod 3) and a(n) = 0 is n = 4477. - Alois P. Heinz, Oct 30 2019
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..20000
FORMULA
a(n) = 0 if n = 1 or n == 0 (mod 3). - Alois P. Heinz, Oct 30 2019
EXAMPLE
1(-), 2(11), 3(-), 4(13, 31), 5(23, 41), 6(-), 7(43, 61), 8(17, 53, 71), 9(-), 10(19, 37, 73), 11(29, 47, 83, 101), 12(-), 13(67, 103, 211), ...
MAPLE
a:= proc(n) option remember; `if`(irem(n, 3)=0, 0, add(
`if`(isprime(parse(cat(i, n-i))), 1, 0), i=1..n-1))
end:
seq(a(n), n=0..100); # Alois P. Heinz, Oct 30 2019
CROSSREFS
KEYWORD
AUTHOR
Juri-Stepan Gerasimov, Oct 30 2019
EXTENSIONS
More terms from Alois P. Heinz, Oct 30 2019
STATUS
approved