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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A379646 Irregular triangle T(n,k) where row n contains the trajectory of recursive mappings of A001175(x) starting with x = n and ending at fixed point A235249(n).

Original entry on oeis.org

1, 2, 3, 8, 12, 24, 3, 8, 12, 24, 4, 6, 24, 5, 20, 60, 120, 6, 24, 7, 16, 24, 8, 12, 24, 9, 24, 10, 60, 120, 11, 10, 60, 120, 12, 24, 13, 28, 48, 24, 14, 48, 24, 15, 40, 60, 120, 16, 24, 17, 36, 24, 18, 24, 19, 18, 24, 20, 60, 120, 21, 16, 24, 22, 30, 120, 23, 48, 24
Offset: 1

Views

Author

Michael De Vlieger, Dec 30 2024

Keywords

Comments

Row n contains recursive mappings of A001175(x) starting with x = n.

Examples

			Table begins:
   1;
   2,  3,   8,  12, 24;
   3,  8,  12,  24;
   4,  6,  24;
   5, 20,  60, 120;
   6, 24;
   7, 16,  24;
   8, 12,  24;
   9, 24;
  10, 60, 120;
  11, 10,  60, 120;
  12, 24;
  ...
		

Crossrefs

Programs

  • Mathematica
    q[{0, 1, }] := False; q[] := True;
    f[k_][{a_, b_, c_}] := {Mod[b, k], Mod[a + b, k], c + 1};
    s[1] := 1; s[k_] := s[k] = Which[
      PrimeQ[k] && k > 5, If[
        AnyTrue[PrimitiveRootList[k], Mod[#^2, k] == Mod[# + 1, k] &],
        k - 1,
        NestWhile[f[k], {1, 1, 1}, q][[-1]] ],
      PrimePowerQ[k], NestWhile[f[k], {1, 1, 1}, q][[-1]], True,
        LCM @@ Map[s[#] &, Power @@@ FactorInteger[k] ] ];
    Table[Most@ FixedPointList[s[#] &, n], {n, 24}]

A001179 Leonardo logarithm of n.

Original entry on oeis.org

0, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 2, 1, 1, 3, 1, 1, 1, 1, 2, 2, 1, 2, 1, 2, 1, 1, 1, 1, 2, 2, 1, 2, 2, 2, 1, 1, 1, 1, 3, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 2, 2, 1, 1, 1, 2, 2, 1
Offset: 1

Views

Author

Keywords

Comments

Are the powers of 5 (together with 2) the indices of records in this sequence? - Charles R Greathouse IV, Aug 11 2022

References

  • B. H. Hannon and W. L. Morris, Tables of Arithmetical Functions Related to the Fibonacci Numbers. Report ORNL-4261, Oak Ridge National Laboratory, Oak Ridge, Tennessee, Jun 1968.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Programs

  • Haskell
    a001179 1 = 0
    a001179 n = if p == n then ll (p `div` 24) 1 else a001179 p
                where p = a001175 n
                      ll x k = if x == 1 then k else ll (x `div` 5) (k + 1)
    -- Reinhard Zumkeller, Jan 15 2014

Formula

A235249(n) = 24*5^(a(n)-1) for n > 1. - Reinhard Zumkeller, Jan 15 2014
Showing 1-2 of 2 results.