OFFSET
0,3
LINKS
Eric Weisstein's World of Mathematics, Cuban Prime
EXAMPLE
7, 19, 37, 61, 127 are the first few cuban primes, so a(1)=1 and a(2)=4.
PROG
(PARI) A113478(n)=sum(k=1, sqrt(10^n/3), isprime(3*k*(k+1)+1)) \\ M. F. Hasler, Nov 28 2007
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Eric W. Weisstein, Jan 10 2006
EXTENSIONS
a(15)-a(18) from Donovan Johnson, Feb 05 2010
a(19)-a(24) from Hiroaki Yamanouchi, Oct 08 2015
STATUS
approved