OFFSET
0,1
FORMULA
a(n) = 2*Floor(3^((2n + 1)/2)) + 1.
EXAMPLE
a(2)=31 because 3^(2*2+1)=3^5=243, 15^2<243<16^2 and 16^2-15^2=256-225=31.
MATHEMATICA
f[n_] := 2*Floor[3^((2n + 1)/2)] + 1; Table[f[n], {n, 0, 25}] (* Ray Chandler, Jun 09 2006 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Zak Seidov, May 27 2006
EXTENSIONS
Extended by Ray Chandler, Jun 09 2006
STATUS
approved