cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A346593 Numbers k such that A006577(k^3) sets a new record.

Original entry on oeis.org

2, 3, 6, 7, 14, 15, 25, 41, 45, 71, 79, 153, 233, 235, 470, 503, 707, 741, 1482, 2964, 3039, 3581, 7162, 14324, 27337, 54674, 61683, 123366, 168159, 254251, 302839, 605678, 622699, 947173, 1618687, 3237374, 6474748, 10995401, 13042083, 21767875, 43535750, 48584565
Offset: 1

Views

Author

Hugo Pfoertner, Jul 28 2021

Keywords

Links

Crossrefs

Cf. A006577, A006877, A244638, A346591, A346592.

Programs

  • Mathematica
    s[n_]:=s[n]=(i=0;r=n;While[r!=1,i++;If[EvenQ@r,r=r/2,r=r*3+1]];i);
lst={};max=1;Do[t=s[k^3];If[t>max,AppendTo[lst,k];max=t],{k,10^4}];lst (* Giorgos Kalogeropoulos, Jul 28 2021 *)
  • PARI
    a6577(n0)={my(n=n0,k=0);while(n>1,k++;n=if(n%2,3*n+1,n/2));k};
a346593(limit)={msteps=0;for(k=1,limit,my(m=a6577(k^3));if(m>msteps,print1(k,", ");msteps=m))};
a346593(1000000)

A346591 Composite numbers k such that A006577(k) sets a new record.

Original entry on oeis.org

4, 6, 9, 18, 25, 27, 54, 108, 129, 171, 231, 327, 649, 703, 871, 1161, 2223, 2463, 2919, 3711, 6171, 10971, 13255, 17647, 23529, 26623, 34239, 35655, 52527, 77031, 106239, 142587, 156159, 216367, 230631, 410011, 511935, 626331, 837799, 1117065, 1501353, 1723519
Offset: 1

Views

Author

Hugo Pfoertner, Jul 28 2021

Keywords

Links

Crossrefs

Cf. A006577, A346592, A346593.
A006877 is the union of A244638 and this sequence.

Programs

  • Mathematica
    s[n_]:=s[n]=(i=0;r=n;While[r!=1,i++;If[EvenQ@r,r=r/2,r=r*3+1]];i);
lst={};max=1;Do[If[!PrimeQ@k,t=s[k];If[t>max,AppendTo[lst,k];max=t]],{k,10^4}];lst (* Giorgos Kalogeropoulos, Jul 28 2021 *)
  • PARI
    a6577(n0)={my(n=n0,k=0);while(n>1,k++;n=if(n%2,3*n+1,n/2));k};
a346591(limit)={msteps=0;forcomposite(c=4,limit,my(m=a6577(c));if(m>msteps,print1(c,", ");msteps=m))};
a346591(2000000)

A346782 Numbers k such that A006577(k!) sets a new record.

Original entry on oeis.org

2, 3, 4, 5, 7, 8, 9, 11, 12, 14, 17, 21, 26, 29, 33, 34, 37, 44, 45, 47, 48, 51, 52, 55, 58, 61, 70, 78, 85, 89, 91, 92, 93, 96, 97, 98, 105, 107, 113, 114, 118, 124, 129, 135, 145, 148, 149, 150, 152, 157, 161, 173, 175, 179, 184, 192, 201, 205, 206, 209, 212, 213
Offset: 1

Views

Author

Hugo Pfoertner, Aug 04 2021

Keywords

Crossrefs

The corresponding record numbers of steps are A346783.
Cf. A006577, A070974, A346592, A346593.

Programs

  • PARI
    a6577(n0)={my(n=n0,k=0);while(n>1,k++;n=if(n%2,3*n+1,n/2));k};
a346782(limit)={my(msteps=0);for(k=0,limit,my(m=a6577(k!));if(m>msteps,print1(k,", ");msteps=m))};
a346782(215)
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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