A286380 a(n) = the minimum number of iterations of the reduced Collatz function R required to yield 1. The function R (A139391) is defined as R(k) = (3k+1)/2^r, with r as large as possible.

0, 1, 2, 1, 1, 3, 5, 1, 6, 2, 4, 3, 2, 6, 5, 1, 3, 7, 6, 2, 1, 5, 4, 3, 7, 3, 41, 6, 5, 6, 39, 1, 8, 4, 3, 7, 6, 7, 11, 2, 40, 2, 9, 5, 4, 5, 38, 3, 7, 8, 7, 3, 2, 42, 41, 6, 10, 6, 10, 6, 5, 40, 39, 1, 8, 9, 8, 4, 3, 4, 37, 7, 42, 7, 3, 7, 6, 12, 11, 2, 6, 41, 40, 2, 1, 10, 9, 5, 9, 5, 33, 5, 4, 39, 38, 3, 43, 8, 7, 8, 7, 8, 31, 3, 12, 3, 36, 42, 41, 42, 24

Offset

1,3

Links

Antti Karttunen, Table of n, a(n) for n = 1..10000

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

Formula

a(1) = 0; for n > 1, a(n) = 1 + a(A139391(n)).

Other identities. For all n >= 1:

a(n) + A000035(n) = A078719(n).

Prog

(Scheme) (define (A286380 n) (if (= 1 n) 0 (+ 1 (A286380 (A139391 n)))))

Crossrefs

Cf. A075680 (the odd bisection).

Cf. A078719, A139391.

Sequence in context: A290569 A230698 A090234 * A275866 A007754 A144866

Adjacent sequences: A286377 A286378 A286379 * A286381 A286382 A286383

Keyword

nonn

Author

Antti Karttunen, May 08 2017

Status

approved