OFFSET
1,1
COMMENTS
FORMULA
a(n) = A000040(a(p+3q) = a(p)+3q) with p and q positive integers.
a(n) = PrimePi(a(p+3q) = a(p)+3q) with p and q positive integers.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Oct 17 2006, Nov 08 2006
STATUS
approved