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A056957 In repeated iterations of function m->m/2 if m even, m->3m-1 if m odd, a(n) is minimum value achieved if starting from n. 1
1, 1, 1, 1, 5, 1, 5, 1, 5, 5, 1, 1, 5, 5, 1, 1, 17, 5, 5, 5, 17, 1, 17, 1, 17, 5, 5, 5, 1, 1, 17, 1, 17, 17, 5, 5, 17, 5, 1, 5, 17, 17, 1, 1, 17, 17, 5, 1, 17, 17, 5, 5, 1, 5, 17, 5, 1, 1, 1, 1, 17, 17, 5, 1, 1, 17, 17, 17, 1, 5, 1, 5, 17, 17, 5, 5, 1, 1, 1, 5, 5, 17, 17, 17, 1, 1, 1, 1, 5, 17 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

At least for n<10000, the only possible cycles reached include 1,2,1,..., 5,14,7,20,10,5,... and 17,50,25,74,37,110,55,164,82,41,122,61,182,91,272,136,68,34,17,... For n<5 only the first occurs, while for n<17 only the first two occur.

LINKS

Table of n, a(n) for n=1..90.

FORMULA

a(2n) = a(n)

EXAMPLE

a(9)=5 since iteration starts: 9, 26, 13, 38, 19, 56, 28, 14, 7, 20, 10, 5, 14, 7, 20, 10, 5, ... and 5 is the smallest value

CROSSREFS

Cf. A001281. If n is in A039500 then a(n)=1, if n is in A039501 then a(n)=5, if n is in A039502 then a(n)=17. If n is negative then this becomes the 3x+1 problem and the minimum values become those which are most negative (i.e. maximum absolute values) as in A056959.

Sequence in context: A339353 A050349 A083528 * A224834 A095118 A251417

Adjacent sequences:  A056954 A056955 A056956 * A056958 A056959 A056960

KEYWORD

nonn

AUTHOR

Henry Bottomley, Jul 18 2000

EXTENSIONS

Edited by Bryce Herdt (mathidentity(AT)yahoo.com), Apr 18 2010

STATUS

approved

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Last modified September 17 15:51 EDT 2021. Contains 347478 sequences. (Running on oeis4.)