OFFSET
1,4
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
EXAMPLE
a(10) = #{59,61,67,71,73,79,83,89,97} = 9;
a(11) = #{67,71,73,79,83,89,97,101,103,107,109,113} = 12;
a(12) = #{79,83,89,97,101,103,107,109,113,127,131,137,139} = 13.
MATHEMATICA
Table[PrimePi[n^2] - PrimePi[n*(n+1)/2], {n, 100}] (* T. D. Noe, Nov 01 2011 *)
PrimePi[#[[2]]]-PrimePi[#[[1]]]&/@Module[{nn=70}, Thread[{Accumulate[ Range[ nn]], Range[nn]^2}]] (* Harvey P. Dale, Aug 21 2019 *)
PROG
(Haskell)
a194189 n = sum $ map a010051 [n*(n+1) `div` 2 + 1 .. n^2 - 1]
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Nov 01 2011
STATUS
approved