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Search: id:A095810
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| A095810 |
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Numbers of the form 2^j (mod 10^k), where j and k are any positive integers, with leading zeros suppressed. |
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+0
4
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| 1, 2, 4, 6, 8, 12, 16, 24, 28, 32, 36, 44, 48, 52, 56, 64, 68, 72, 76, 84, 88, 92, 96, 104, 112, 128, 136, 144, 152, 168, 176, 184, 192, 208, 216, 224, 232, 248, 256, 264, 272, 288, 296, 304, 312, 328, 336, 344, 352, 368, 376, 384, 392, 408, 416, 424, 432, 448
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Given only the last 5 (say) digits of a large integer N, how can you determine if N is not some power of 2? That is, which 5-digit numbers are of the form 2^j (mod 10^6) where j is any positive integer? So if the last 5 digits of N were not in this sequence, then N would not be a power of 2.
If we have only the last k digits of a large integer N, you find that N is not a power of 2 if and only if the number given by those digits is divisible by 5 OR not a multiple of 2^k OR a value > 2^k*(5^k-1). - Francisco Salinas (franciscodesalinas(at)hotmail.com), Aug 27 2004.
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MATHEMATICA
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Take[ Union[ Flatten[ Table[ PowerMod[2, j, 10^k], {j, 0, 100}, {k, 3}]]], 58] (from Robert G. Wilson v (rgwv(at)rgwv.com) Sep 11 2004)
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CROSSREFS
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Cf. A097574, A113022, A113023.
Sequence in context: A065386 A048951 A058629 this_sequence A025487 A070175 A096850
Adjacent sequences: A095807 A095808 A095809 this_sequence A095811 A095812 A095813
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KEYWORD
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nonn
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AUTHOR
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Paul D. Hanna (pauldhanna(AT)juno.com), Aug 30 2004
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EXTENSIONS
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Additional comments from Robert G. Wilson v, Oct 11 2005
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