A094669 Number of halving and tripling steps for 10^n to reach 1 in '3x+1' problem.

6, 25, 111, 29, 128, 152, 145, 107, 100, 124, 347, 146, 289, 194, 275, 255, 235, 303, 340, 470, 357, 324, 454, 266, 564, 433, 470, 331, 492, 467, 584, 515, 614, 550, 711, 497, 653, 1039, 577, 694, 749, 755, 779, 666, 752, 913, 769, 754, 724, 691, 883, 827, 683

Offset

1,1

Links

Michael S. Branicky, Table of n, a(n) for n = 1..10000

Index entries for sequences related to 3x+1 (or Collatz) problem

Formula

a(n) = A006577(A011557(n)). - Michel Marcus, Jun 25 2021

Prog

(Python)
def f(x): return x//2 if x%2 == 0 else 3*x + 1
def a(n):
    i, c = 10**n, 0
    while i != 1: i, c = f(i), c+1
    return c
print([a(n) for n in range(1, 54)]) # Michael S. Branicky, Jun 25 2021

Crossrefs

Cf. A006577, A011557.

Sequence in context: A048875 A295202 A346894 * A100296 A346818 A120758

Adjacent sequences: A094666 A094667 A094668 * A094670 A094671 A094672

Keyword

easy,nonn

Author

Jason Earls, Jun 07 2004

Extensions

a(53) and beyond from Michael S. Branicky, Jun 25 2021

Status

approved