OFFSET

1,2

COMMENTS

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..100000

FORMULA

For n <= 5, a(n) = n, for >= 5, a(n) = 5 when n is a prime, and a(n) = 3+n-A000720(n) when n is a composite.

PROG

(PARI) A305900(n) = if(n<=5, n, if(isprime(n), 5, 3+n-primepi(n)));

CROSSREFS

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 14 2018

STATUS

approved