OFFSET
0,1
COMMENTS
a(n) is the number of lattice points inside spiral r=theta and on X-axis counted until the (n+1)-th loop of the spiral.
LINKS
César Eliud Lozada, Plot of spiral
FORMULA
a(n) = floor((2*n+1)*Pi) + floor((2*n+2)*Pi) + 1.
MAPLE
A := []:
for n from 0 to 80 do
n1 := floor((2*n+1)*Pi):
n2 := floor((2*n+2)*Pi):
A := [op(A), n1+n2+1]
end do:
A:=A;
MATHEMATICA
Table[Ceiling[Pi(2n+2)]+Floor[Pi(2n+1)], {n, 0, 60}] (* Harvey P. Dale, Aug 25 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
César Eliud Lozada, Oct 08 2012
STATUS
approved