public SmaSeries(ISeries<decimal> parent, int periods, TierKind? runOnTier = null)

new object[]
 {
    new DecimalSeries(),
    20,
    new Nullable<TierKind>(TierKind.Client)
 }

//DecimalSeries implements ISeries<decimal>

using System;

class SmaSeries
{
    public SmaSeries(ISeries<decimal> parent, int periods,
         TierKind? runOnTier = null) { }
    static void Main()
    {
        object[] args = new object[]
         {
            new DecimalSeries(),
            20,
            new Nullable<TierKind>(TierKind.Client)
         };

        object obj = Activator.CreateInstance(typeof(SmaSeries), args);
    }
}
enum TierKind { Client }
interface ISeries<T> { }
class DecimalSeries : ISeries<decimal> { }