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Search: id:A069705
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| 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4, 1, 2, 4
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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3x+1 sequence starting at 1 - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 25 2006.
Periodic sequence with period [1,2,4] . - Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 25 2006
a(n) = cubefree part of 2^n (n=0,1,2,3,...) [From Artur Jasinski (grafix(AT)csl.pl), Oct 15 2008]
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FORMULA
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n=0 mod 3 -> a(n)=1 n=1 mod 3 -> a(n)=2 n=2 mod 3 -> a(n)=4
a(n)=2^mod(n, 3) - Paul Barry (pbarry(AT)wit.ie), Oct 06 2003
a(n)=1/9*{16*(n mod 3)+[(n+1) mod 3]+4*[(n+2) mod 3]} - Paolo P. Lava (ppl(AT)spl.at), Nov 21 2006
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EXAMPLE
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a(4)=16 mod 7=2, a(5)=32 mod 7=4, a(6)=64 mod 7=1
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MATHEMATICA
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CubefreePart[n_Integer?Positive] := Times @@ Power @@@ ({#[[1]], Mod[ #[[2]], 3]} & /@ FactorInteger[n]); Table[CubefreePart[2^n], {n, 0, 400}] [From Artur Jasinski (grafix(AT)csl.pl), Oct 15 2008]
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PROGRAM
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(Other) sage: [power_mod(2, n, 7)for n in xrange(0, 105)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Jun 07 2009]
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CROSSREFS
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A145642 [From Artur Jasinski (grafix(AT)csl.pl), Oct 15 2008]
Sequence in context: A053450 A124911 A132954 this_sequence A106645 A115314 A062039
Adjacent sequences: A069702 A069703 A069704 this_sequence A069706 A069707 A069708
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KEYWORD
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nonn
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AUTHOR
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Jon Perry (perry(AT)globalnet.co.uk), Jan 14 2003
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