Mine

// based on D
import java.lang.Math;

public final class partialsums
{
 public static void main(String[] args)
{
    double n = Integer.parseInt(args[0]) + 1, alt = 1;
    double sum0=0, sum1=0, sum2=0, sum3=0, sum4=0, sum5=0, sum6=0, sum7=0, sum8=0;

    for(double d = 1; d < n; d++, alt = -alt)
    {
        double d2 = d * d, d3 = d2 * d;
        double ds = Math.sin(d), dc = Math.cos(d);

        sum0 += Math.pow(2 / 3d,d - 1);
        sum1 += 1 / Math.sqrt(d);
        sum2 += 1 / (d * (d + 1));

        //  Flint Hills
        sum3 += 1 / (d3 * ds * ds);
        //  Cookson Hills
        sum4 += 1 / (d3 * dc * dc);

        //  Harmonic
        sum5 += 1 / d;
        //  Riemann Zeta
        sum6 += 1 / (d2);

        //  Alternating Harmonic
        sum7 += alt / d;
        //  Gregory
        sum8 += alt / (2 * d - 1);
    }

      System.out.printf("%.9f\t(2/3)^k\n", sum0);
      System.out.printf("%.9f\tk^-0.5\n", sum1);
      System.out.printf("%.9f\t1/k(k+1)\n", sum2);
      System.out.printf("%.9f\tFlint Hills\n", sum3);
      System.out.printf("%.9f\tCookson Hills\n", sum4);
      System.out.printf("%.9f\tHarmonic\n", sum5);
      System.out.printf("%.9f\tRiemann Zeta\n", sum6);
      System.out.printf("%.9f\tAlternating Harmonic\n", sum7);
      System.out.printf("%.9f\tGregory\n", sum8);
}

}