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Search: id:A136273
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| A136273 |
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a(0) = 0; for n>0, a(n) = period length of the decimal expansion of the number Sum_{i=1..oo} 2^(-n*i). Also period length of the fractions 1/b(n), where b(n)=2*b(n-1)+1, with b(1)=1. |
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+0
1
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| 0, 1, 6, 1, 15, 6, 42, 16, 24, 30, 44, 6, 1365, 42, 150, 256, 3855, 72, 74898, 30, 336, 1364, 44620, 240, 900, 2730, 262656, 336, 39672, 1650, 195225786, 65536, 1198956, 131070, 92190, 216, 616318176, 524286, 2123940, 61680, 26815350376, 43344
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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In base 2 consider the numbers 0.1111111..., 0.01010101...., 0.001001001..., 0.000100010001.... where the period [0 k times, 1], where k=0,1,2,3.... Then convert to base 10. The sequence gives the length of each period.
The period length of the fraction 1/A000225(n) = 1/(2^n-1) for n>0. - Robert G. Wilson v, (rgwv(AT)rgwv.com), Mar 30 2008
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MATHEMATICA
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f[n_] := Length[RealDigits[Sum[2^(-n*k), {k, Infinity}]][[1, 1]]]; Array[f, 36] - Robert G. Wilson v, (rgwv(AT)rgwv.com), Mar 30 2008
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CROSSREFS
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Adjacent sequences: A136270 A136271 A136272 this_sequence A136274 A136275 A136276
Sequence in context: A147483 A050309 A103217 this_sequence A125233 A139727 A049325
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KEYWORD
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easy,nonn
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AUTHOR
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Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), Mar 19 2008
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EXTENSIONS
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More terms from Robert G. Wilson v, (rgwv(AT)rgwv.com), Mar 30 2008
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