OFFSET
0,2
FORMULA
a(n)=A101264(n), n>1. [From R. J. Mathar, Dec 13 2008]
EXAMPLE
a(1)=2 because between 2 and 4 there are two primes: 2,3;
a(2)=1 because between 4 and 6 there is one prime: 5;
a(4)=0 because between 8 and 10 there are no primes.
PROG
(PARI) a(n) = if (n==0, 1, if (n==1, 2, isprime(2*n+1))) \\ Michel Marcus, Jun 03 2013
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Jan 27 2005
STATUS
approved