OFFSET
1,1
COMMENTS
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
a(4) = #{293,307,311,313,317,331,337,347,349,353,359} = 11.
MATHEMATICA
PrimePi[#[[2]]^2]-PrimePi[#[[1]]^2]&/@Select[Partition[ Prime[ Range[ 200]], 2, 1], #[[2]]-#[[1]]==2&] (* Harvey P. Dale, Nov 10 2017 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Feb 16 2008
STATUS
approved