Task: Fibonacci n-step number sequences
C#: using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Fibonacci
{
    class Program
    {
        static void Main(string[] args)
        {
            PrintNumberSequence("Fibonacci", GetNnacciNumbers(2, 10));
            PrintNumberSequence("Lucas", GetLucasNumbers(10));
            PrintNumberSequence("Tribonacci", GetNnacciNumbers(3, 10));
            PrintNumberSequence("Tetranacci", GetNnacciNumbers(4, 10));
            Console.ReadKey();
        }

        private static IList<ulong> GetLucasNumbers(int length)
        {
            IList<ulong> seedSequence = new List<ulong>() { 2, 1 };
            return GetFibLikeSequence(seedSequence, length);
        }

        private static IList<ulong> GetNnacciNumbers(int seedLength, int length)
        {
            return GetFibLikeSequence(GetNacciSeed(seedLength), length);
        }

        private static IList<ulong> GetNacciSeed(int seedLength)
        {
            IList<ulong> seedSquence = new List<ulong>() { 1 };

            for (uint i = 0; i < seedLength - 1; i++)
            {
                seedSquence.Add((ulong)Math.Pow(2, i));
            }

            return seedSquence;
        }

        private static IList<ulong> GetFibLikeSequence(IList<ulong> seedSequence, int length)
        {
            IList<ulong> sequence = new List<ulong>();

            int count = seedSequence.Count();

            if (length <= count)
            {
                sequence = seedSequence.Take((int)length).ToList();
            }
            else
            {
                sequence = seedSequence;

                for (int i = count; i < length; i++)
                {
                    ulong num = 0;

                    for (int j = 0; j < count; j++)
                    {
                        num += sequence[sequence.Count - 1 - j];
                    }

                    sequence.Add(num);
                }
            }

            return sequence;
        }

        private static void PrintNumberSequence(string Title, IList<ulong> numbersequence)
        {
            StringBuilder output = new StringBuilder(Title).Append("   ");

            foreach (long item in numbersequence)
            {
                output.AppendFormat("{0}, ", item);
            }

            Console.WriteLine(output.ToString());
        }
    }
}

C++: #include <vector>
#include <iostream>
#include <numeric>
#include <iterator>
#include <memory>
#include <string>
#include <algorithm>
#include <iomanip>

std::vector<int> nacci ( const std::vector<int> & start , int arity ) {
   std::vector<int> result ( start ) ;
   int sumstart = 1 ;
                     
   while ( result.size( ) < 15 ) { 
      if ( result.size( ) <= arity ) 
	 result.push_back( std::accumulate( result.begin( ) , 
		  result.begin( ) + result.size( ) , 0 ) ) ;
      else { 
	 result.push_back( std::accumulate ( result.begin( ) +
	  sumstart , result.begin( ) + sumstart + arity  , 0 )) ;
	 sumstart++ ;
      }
   }
   return std::move ( result ) ;
}

int main( ) {
   std::vector<std::string> naccinames {"fibo" , "tribo" , 
      "tetra" , "penta" , "hexa" , "hepta" , "octo" , "nona" , "deca" } ;
   const std::vector<int> fibo { 1 , 1 } , lucas { 2 , 1 } ;
   for ( int i = 2 ; i < 11 ; i++ ) {
      std::vector<int> numberrow = nacci ( fibo , i ) ;
      std::cout << std::left << std::setw( 10 ) << 
	 naccinames[ i - 2 ].append( "nacci" ) <<
	 std::setw( 2 ) << " : " ;
      std::copy ( numberrow.begin( ) , numberrow.end( ) ,
	    std::ostream_iterator<int>( std::cout , " " ) ) ; 
      std::cout << "...\n" ;
      numberrow = nacci ( lucas , i ) ;
      std::cout << "Lucas-" << i ; 
      if ( i < 10 )               
	 std::cout << "    : " ;
      else 
	 std::cout << "   : " ;
      std::copy ( numberrow.begin( ) , numberrow.end( ) ,
	    std::ostream_iterator<int>( std::cout , " " ) ) ; 
      std::cout << "...\n" ;
   }
   return 0 ;
}