OFFSET
1,2
FORMULA
(See the Mathematica code.)
MATHEMATICA
a=1/2; b=7/2;
F[n_]:=a*n^2+b*n;
R[n_]:=(n/a+((b-1)/(2a))^2)^(1/2);
G[n_]:=n-1+Ceiling[R[n]-(b-1)/(2a)];
Table[F[n], {n, 60}]
Table[G[n], {n, 100}]
PROG
(PARI) a(n)=n-1+ceil(sqrt(8*n+25)/2-5/2) \\ Charles R Greathouse IV, Jan 20 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Jan 03 2011
STATUS
approved