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Search: id:A007843
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| A007843 |
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Least positive integer k for which 2^n divides k!. |
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+0
11
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| 1, 2, 4, 4, 6, 8, 8, 8, 10, 12, 12, 14, 16, 16, 16, 16, 18, 20, 20, 22, 24, 24, 24, 26, 28, 28, 30, 32, 32, 32, 32, 32, 34, 36, 36, 38, 40, 40, 40, 42, 44, 44, 46, 48, 48, 48, 48, 50, 52, 52, 54, 56, 56, 56, 58, 60, 60, 62, 64, 64, 64, 64, 64, 64, 66, 68, 68, 70, 72, 72, 72, 74, 76, 76, 78
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Obtained by writing every natural number n k times where 2^k divides n but 2^(k+1) does not divide n. - Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Aug 22 2002
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REFERENCES
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H. Ibstedt, Smarandache Primitive Numbers, Smarandache Notions Journal, Vol. 8, No. 1-2-3, 1997, 216-229.
F. Smarandache, "Only Problems, not Solutions!", Xiquan Publ., Phoenix-Chicago, 1993.
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LINKS
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T. D. Noe, Table of n, a(n) for n=0..1000
M. L. Perez et al., eds., Smarandache Notions Journal
F. Smarandache, Only Problems, Not Solutions!.
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FORMULA
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a(n)=A002034(2^n). For n>1, it appears that a(n+1)=a(n)+2 if n is in A005187. - Benoit Cloitre (benoit7848c(AT)orange.fr), Sep 01 2002
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MAPLE
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with(numtheory): ans := [ ]: p := ithprime(1): t0 := 1/p: for n from 0 to 50 do t0 := t0*p: t1 := 1: i := 1: while t1 mod t0 <> 0 do i := i+1: t1 := t1*i: od: ans := [ op(ans), i ]: od: ans;
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PROGRAM
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(PARI) a(n)=if(n<0, 0, s=1; while(s!%(2^n)>0, s++); s)
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CROSSREFS
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Cf. A007844, A007845, A020646, A048841-A048846.
Sequence in context: A135692 A089003 A132118 this_sequence A053196 A002131 A063200
Adjacent sequences: A007840 A007841 A007842 this_sequence A007844 A007845 A007846
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KEYWORD
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nonn,easy,nice
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AUTHOR
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Bruce Dearden and Jerry Metzger (metzger(AT)rs1.cc.und.nodak.edu); R. Muller
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