A375909 Number of iterations of the Farkas map (A349407) to reach 1 starting from 2*n - 1.

0, 1, 2, 5, 2, 4, 6, 3, 3, 5, 6, 6, 7, 3, 4, 9, 5, 5, 6, 7, 7, 7, 4, 8, 8, 4, 4, 10, 6, 6, 10, 7, 6, 6, 7, 7, 7, 8, 8, 9, 4, 9, 8, 5, 5, 9, 10, 10, 9, 6, 5, 11, 6, 6, 11, 7, 7, 7, 8, 8, 11, 8, 8, 13, 8, 8, 7, 5, 8, 8, 9, 9, 8, 9, 9, 10, 5, 10, 10, 5, 5, 10, 11, 11, 9

Offset: 1

Author

Paolo Xausa, Sep 02 2024

Keywords

• nonn
• easy

Examples

			a(10) = 5 because the trajectory 19 -> 29 -> 15 -> 5 -> 3 -> 1 takes 5 steps.
		

Links

• Paolo Xausa, Table of n, a(n) for n = 1..10000

Crossrefs

(Row lengths of A350279) - 1.

Cf. A006577, A006666, A349407, A375267, A375911.

Programs

Mathematica

FarkasStep[x_] := Which[Divisible[x, 3], x/3, Mod[x, 4] == 3, (3*x + 1)/2, True, (x + 1)/2];
Array[Length[FixedPointList[FarkasStep, 2*# - 1]] - 2 &, 100]