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Search: id:A028397
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| A028397 |
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Start at n and iterate the map in A006368 until it cycles; a(n) is the smallest number in cycle (some cycles are infinite). |
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+0
4
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| 0, 1, 2, 2, 4, 4, 4, 4, 8, 4, 8, 8, 12, 8, 14, 8, 16, 8, 18, 14, 20, 16, 14, 8, 24, 14, 14, 20, 14, 14, 30, 8, 32, 14, 32, 14, 36, 14, 32, 14, 40, 8, 14, 32, 44, 32, 46, 14, 48, 14, 50, 32, 50, 40, 46, 8, 56, 32, 14, 44, 60, 46, 44, 14, 64, 14, 44, 50, 8, 50, 44, 40, 72, 8, 44, 56
(list; graph; listen)
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OFFSET
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0,3
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..1000
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EXAMPLE
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Sample iteration: 7->5->4->6->9->7 so a(7)=4.
Sample iteration: 12->18->27->20->30->45->34->51->... so a(12)=12.
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PROGRAM
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(Perl) $|=1; for($n=1; ; ++$n){ $m=$n; $d{$m}=$n, $m=f($m) while !$d{$m};
(Perl) if ($m<$n){ ($c, $m)=($d{$m}, $n); $d{$m}=$c, $m=f($m) while $m >= $n }
(Perl) print"$d{$n}, " } sub f { $_[0]%2 ? int((3*$_[0]+1)/4) : 3*$_[0]/2 }
(PARI) a(n)=local(m); if(n<=0, 0, m=n; while((m!=n=(3*n+n%2)\(2+n%2*2))&n<10^99, m=min(m, n)); m)
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CROSSREFS
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Sequence in context: A076222 A098667 A105678 this_sequence A053644 A039593 A101656
Adjacent sequences: A028394 A028395 A028396 this_sequence A028398 A028399 A028400
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KEYWORD
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nonn,nice
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AUTHOR
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njas and J. H. Conway (conway(AT)math.princeton.edu)
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EXTENSIONS
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More terms from Hugo van der Sanden (hv(AT)crypt.org)
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