OFFSET
2,2
LINKS
Harvey P. Dale, Table of n, a(n) for n = 2..1000
FORMULA
Sum(floor((n^2-1)/i)+1-i, i=2..n)
EXAMPLE
f(3)=3 because the only pairs of 2 numbers > 1 that are < 9 are (2,2) (2,3) (2,4).
MATHEMATICA
Table[Sum[Floor[(n^2-1)/i]+1-i, {i, 2, n}], {n, 2, 45}] (* Harvey P. Dale, Oct 10 2011 *)
KEYWORD
nonn
AUTHOR
Joe K. Crump (joecr(AT)carolina.rr.com)
STATUS
approved