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Search: id:A129344
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| A129344 |
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a(n) is the number of powers of 2 that have n decimal digits. |
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+0
2
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| 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 4, 3, 3, 3, 4, 3, 3
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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a(1) is 4 because there are 4 one-digit powers of 2: 1, 2, 4, 8.
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MATHEMATICA
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Table[Transpose[ Select[Table[{n, 2^n}, {n, 0, 310}], IntegerDigits[ #[[2]]][[1]] == 1 &]][[1]][[k]] - Transpose[ Select[Table[{n, 2^n}, {n, 0, 310}], IntegerDigits[ #[[2]]][[1]] == 1 &]][[1]][[k - 1]], {k, 2, 94}]
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CROSSREFS
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The difference of A067497 - Smallest power of 2 with n+1 digits (n>=0). Also n such that 1 is the first digit of 2^n.
Sequence in context: A085415 A059124 A026858 this_sequence A048853 A011762 A063571
Adjacent sequences: A129341 A129342 A129343 this_sequence A129345 A129346 A129347
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KEYWORD
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base,nonn
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AUTHOR
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Tanya Khovanova (tanyakh(AT)yahoo.com), May 28 2007
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