OFFSET
1,30
EXAMPLE
a(4)=1 because between prime(4)=7 and prime(5)=11 there is one number of the form 6k+3: 9.
MATHEMATICA
f[n_] := Count[Table[Mod[k, 6], {k, Prime[n], Prime[n + 1] - 1}], 3]; Table[f[n], {n, 120}] (* Ray Chandler, Oct 17 2006 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, May 02 2005
EXTENSIONS
Corrected and extended by Ray Chandler, Oct 17 2006
STATUS
approved