A318759 Numbers x whose trajectory reaches 1 under recursive applications of the map x -> x/3 if x == 0 (mod 3), x -> (4*x+2)/3 if x == 1 (mod 3), x -> (4*x+1)/3 if x == 2 (mod 3).

1, 2, 3, 4, 6, 9, 12, 13, 18, 20, 27, 29, 36, 39, 40, 54, 60, 65, 81, 87, 108, 109, 117, 120, 121, 136, 146, 162, 180, 182, 195, 197, 243, 245, 261, 263, 272, 324, 327, 328, 332, 351, 360, 363

Offset

1,2

Links

Table of n, a(n) for n=1..44.

Prog

(C++)
#include <iostream>
using namespace std;
void Number_Generator();
int main()
{
    Number_Generator();
    return 0;
}
void Number_Generator()
{
    int Number_Tested=1; int Temporary;
    int Divideby=3;
    //For numbers bigger than this you need to use unsigned long int or do some large number implementation.
    int Limit=38000;
    while(Number_Tested<Limit)
    {
        Temporary=Number_Tested;
        //There are two cycles. 1 and 7 are the smallest numbers in those cycles.
        while((Temporary!=1) && (Temporary!=7))
        {
            if(Temporary%Divideby)
                Temporary=(Temporary*(Divideby+1)+(Divideby-(Temporary%Divideby)))/Divideby;
            else
                Temporary=Temporary/Divideby;
        }
        if(Temporary==1)
            cout<<Number_Tested<<"\n";
        Number_Tested++;
    }
}

Crossrefs

Cf. A014682, A126241, A138754.

Sequence in context: A288734 A332034 A332035 * A018471 A240307 A128166

Adjacent sequences: A318756 A318757 A318758 * A318760 A318761 A318762

Keyword

nonn

Author

Jack Warren, Sep 02 2018

Status

approved