OFFSET
1,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
EXAMPLE
a(3) = 2 because primes 23, 41 are concatenations of prime(3) = 5 = 2 + 3 = 4 + 1.
MAPLE
a:= n-> (p-> add(`if`(isprime(parse(cat(i,
p-i))), 1, 0), i=1..p-1))(ithprime(n)):
seq(a(n), n=1..80); # Alois P. Heinz, Oct 31 2019
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Juri-Stepan Gerasimov, Oct 31 2019
STATUS
approved