

A072410


Number of iterations of the map k > A000001(k) needed to reach 1 starting at n, or 1 if no such number exists.


2



0, 1, 1, 2, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 1, 3, 1, 2, 1, 2, 2, 2, 1, 2, 2, 2, 2, 3, 1, 3, 1, 2, 1, 2, 1, 3, 1, 2, 2, 3, 1, 3, 1, 3, 2, 2, 1, 3, 2, 2, 1, 2, 1, 2, 2, 2, 2, 2, 1, 2, 1, 2, 3, 2, 1, 3, 1, 2, 1, 3, 1, 3, 1, 2, 2, 3, 1, 3, 1, 3, 2, 2, 1, 2, 1, 2, 1, 3, 1, 3, 1, 3, 2, 2, 1, 3, 1, 2, 2, 4, 1, 3, 1, 3, 2
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OFFSET

1,4


COMMENTS

The old entry with this sequence number was a duplicate of A052409.
It appears that a(n) is the number of times n appears in A142978, excluding the first column of infinitely many 1's.  Ron Wolf, Dec 16 2020
Preceding comment is incorrect. The first counterexample is a(19) = 1, whereas 19 appears twice in A142978.  Eric M. Schmidt, Mar 22 2021


LINKS

Eric M. Schmidt, Table of n, a(n) for n = 1..2047 [using data from example and A000001]
John H. Conway, Heiko Dietrich and E. A. O'Brien, Counting groups: gnus, moas and other exotica.


EXAMPLE

Conway et al. remark that every number less than 2048 reaches 1 after at most 5 steps and give the following examples:
672 > 1280 > 1116461 > 1
1024 > 49487365422 > 240 > 208 > 51 > 1
720 > 840 > 186 > 6 > 2 > 1
320 > 1640 > 68 > 5 > 1
384 > 20169 > 67 > 1
128 > 2328 > 64 > 267 > 1
960 > 11394 > 60 > 13 > 1
864 > 4725 > 51 > 1
1344 > 11720 > 49 > 2 > 1
1440 > 5958 > 16 > 14 > 2 > 1
1248 > 1460 > 15 > 1
256 > 56092 > 11 > 1
1728 > 47937 > 6 > 2 > 1
512 > 10494213 > 5 > 1
1536 > 408641062 > 4 > 2 > 1
1664 > 21507 > 2 > 1
1280 > 1116461 > 1


CROSSREFS

Cf. A000001, A066952 (indices of records).
Sequence in context: A052299 A071854 A183025 * A342824 A072491 A051034
Adjacent sequences: A072407 A072408 A072409 * A072411 A072412 A072413


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Oct 03 2008


STATUS

approved



