A106602 Number of primitive positive solutions to 8n+2=x^2+y^2.

1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 1, 2, 0, 1, 0, 0, 2, 1, 0, 1, 1, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 2, 1, 0, 1, 0, 0, 1, 1, 0, 1, 2, 0, 1, 1, 0, 2, 0, 0, 0, 2, 0, 1, 1, 0, 1, 0, 0, 0, 1, 0, 2, 1, 0, 1, 1, 0, 1, 1, 0

Offset: 0

Author

Colin Mallows, May 10 2005

Keywords

• easy
• nonn

Examples

			a(16)=2 because we have 130=11^2+3^2=9^2+7^2. a(2)=0 because although 18=3^2+3^2, these components are not mutually prime.
		

Links

• R. J. Mathar, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A106594.

Programs

Maple

A106602 := proc(n)
    local a,x,y,fourn;
    fourn := 8*n+2 ;
    a := 0 ;
    for x from 1 do
        if x^2 >= fourn then
            return a;
        else
            y := fourn-x^2 ;
            if issqr(y) then
                y := sqrt(y) ;
                if y <= x and igcd(x,y) = 1 then
                    a := a+1 ;
                end if;
            end if;
        end if:
    end do:
end proc: # R. J. Mathar, Sep 21 2013