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Search: id:A020806
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| A020806 |
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Decimal expansion of 1/7. |
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+0
13
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| 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2, 8, 5, 7, 1, 4, 2
(list; cons; graph; listen)
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OFFSET
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0,2
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COMMENT
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A028416(1)=7; A002371(A049084(7))=A002371(4)=6: a(n+6)=a(n), a(n+6/2)=9-a(n). [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 06 2008]
142857 and 999999=7*142857 are first and last Kaprekar numbers with six digits. Note a(n)+a(n+3)=999999999999..=A010734. (142857**2=20408122449;20408+122449=142857). a(n)**2=1,16,4,64,25,49, is a future submission. [From Paul Curtz (bpcrtz(AT)free.fr), Aug 24 2009]
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REFERENCES
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H. Rademacher and O. Toeplitz, Von Zahlen und Figuren (Springer 1930, reprinted 1968), ch. 19, 'Die periodischen Dezimalbrueche'. [From Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Oct 06 2008]
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FORMULA
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a(n)=(1/30)*{39*(n mod 6)-[(n+1) mod 6]+24*[(n+2) mod 6]-21*[(n+3) mod 6]+19*[(n+4) mod 6]-6*[(n+5) mod 6]}, with n>=0 [From Paolo P. Lava (ppl(AT)spl.at), Jan 21 2009]
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CROSSREFS
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Sequence in context: A000727 A030181 A021879 this_sequence A030210 A098798 A131783
Adjacent sequences: A020803 A020804 A020805 this_sequence A020807 A020808 A020809
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KEYWORD
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nonn,cons
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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