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A159999 Number of numbers not greater than n occurring in '3x+1'-trajectory starting with n. +0
5
1, 2, 3, 3, 4, 6, 5, 4, 7, 6, 7, 9, 7, 10, 7, 5, 9, 14, 11, 8, 6, 12, 9, 11, 14, 10, 10, 16, 14, 11, 10, 6, 17, 12, 9, 20, 18, 17, 18, 9, 13, 8, 20, 16, 14, 12, 13, 12, 20, 21, 18, 12, 10, 18, 15, 20, 24, 19, 22, 16, 14, 17, 15, 7, 23, 25, 22, 15, 13, 12, 16, 23, 19, 22, 8, 22, 20, 26, 23 (list; graph; listen)
OFFSET

1,2

COMMENT

a(n) < n for n>6;

a(A033496(n)) = A008908(A033496(n)).

LINKS

R. Zumkeller, Table of n, a(n) for n = 1..10000

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

FORMULA

a(n) = f(n,n,1) with f(n,m,x) = if m=1 then x else f(n, A006370(m), if A006370(m)<n then x+1 else x).

EXAMPLE

a(9) = #{1,2,4,5,7,8,9} = 7, as

9-28-14-7-22-11-34-17-52-26-13-40-20-10-5-16-8-[4-2-1]*

9-..-..-7-..-..-..-..-..-..-..-..-..-..-5-..-8-[4-2-1]*.

CROSSREFS

Sequence in context: A031501 A059442 A014410 this_sequence A003977 A003971 A131187

Adjacent sequences: A159996 A159997 A159998 this_sequence A160000 A160001 A160002

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), May 04 2009

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Last modified November 25 20:09 EST 2009. Contains 167514 sequences.


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