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.

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A216829 2*a(n) is the multiplicative order of 2 mod 3*(2n-1).

Original entry on oeis.org

1, 3, 2, 3, 9, 5, 6, 6, 4, 9, 3, 11, 10, 27, 14, 5, 15, 6, 18, 6, 10, 7, 18, 23, 21, 12, 26, 10, 9, 29, 30, 9, 6, 33, 33, 35, 9, 30, 15, 39, 81, 41, 4, 42, 11, 6, 15, 18, 24, 45, 50, 51, 6, 53, 18, 18, 14, 22, 18, 12, 55, 30, 50, 7, 21, 65, 9, 54, 34, 69, 69
Offset: 1

Views

Author

V. Raman, Sep 17 2012

Keywords

Comments

2*a(n) is the smallest m such that 3*(2n-1) | (2^m+1).
a(n) is the least k such that 2*n-1 is a factor of A002450(k). - Ali Sada, Apr 02 2025

Links

Crossrefs

Cf. A003558, A002326, A216469, A216833, A002450.

Programs

  • GAP
    List([1..70],n->OrderMod(2,3*(2*n-1))/2); # Muniru A Asiru, Feb 26 2019
  • Mathematica
    Table[MultiplicativeOrder[2, 3*(2*n-1)], {n, 100}]/2 (* T. D. Noe, Sep 19 2012 *)
  • PARI
    vector(100,n,znorder(Mod(2,3*(2*n-1)))/2) \\ Joerg Arndt, Sep 14 2012.

Formula

a(n) = A216833(n)/2.

A216469 a(n) = smallest m such that 2n-1 | (2^m+1)/3, or 0 if no such m exists.

Original entry on oeis.org

1, 3, 0, 0, 9, 5, 0, 0, 0, 9, 0, 0, 0, 27, 0, 0, 15, 0, 0, 0, 0, 7, 0, 0, 0, 0, 0, 0, 9, 29, 0, 0, 0, 33, 0, 0, 0, 0, 0, 0, 81, 41, 0, 0, 0, 0, 0, 0, 0, 45, 0, 0, 0, 53, 0, 0, 0, 0, 0, 0, 55, 0, 0, 0, 21, 65, 0, 0, 0, 69, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 81, 0, 0
Offset: 1

Views

Author

V. Raman, Sep 07 2012

Keywords

Crossrefs

Cf. A003558, A002326, A216829, A216833.
Cf. A216833 (multiplicative order of 2 mod 3*(2n-1)).
Cf. A216829 (value of the half of the multiplicative order of 2 mod 3*(2n-1)).

Programs

  • Mathematica
    Table[s = MultiplicativeOrder[2, 3*(2*n-1), {-1}]; If[IntegerQ[s], s, 0], {n, 100}] (* T. D. Noe, Sep 11 2012 *)
  • PARI
    for(i=0,200,i++;m=0;for(x=0,i,x++;if(((2^x+1)/3)%i==0,m=x;break));print1(m",")) \\ V. Raman, Nov 22 2012
Showing 1-2 of 2 results.

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