OFFSET
1,2
FORMULA
a(n) = n + floor(sqrt(-1+4n/3))
MATHEMATICA
a=4/3; b=-1; Table[n+Floor[(a*n+b)^(1/2)], {n, 100}]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Clark Kimberling, Jan 08 2011
STATUS
approved