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Search: id:A141840
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| A141840 |
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a(n) = first term that can be reduced in n steps via repeated interpretation of a(n) as a base b+1 number where b is the largest digit of a(n), such that b is always 6 so that each interpretation is base 7. Terms already fully reduced (i.e. single digits) are excluded. |
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+0
7
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| 16, 64, 631, 1561, 4360, 15466, 63043, 34406005, 565306024
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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It is sometimes possible to compute additional terms by taking the last term, treating it as base 10 and converting to base 7. This may create a term minimally interprettable as base 7 which can converted back to base 10 yielding the previous term in the sequence which will itself yield N further terms. But there is no guarantee (except in base 2) that the term so derived will be the first term to produce a sequence of N+1 terms. There could be another, smaller, term which satisfies that requirement but which uses different terms. Pushing the last term of this sequence does not produce a value minimally interprettable as base 7.
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EXAMPLE
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a(3) = 631 because 631 is the first number that can produce a sequence of three terms by repeated interpetation as a base 7 number: [631] (base-7) --> [316] (base-7) --> [160] (base-7) --> [91]. Since 91 cannot be minimally interpretted as a base 7 number, the sequence terminates with 160. a(1) = 16 because 16 is the first number that can be reduced once, yielding no further terms minimally interprettable as base 7.
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CROSSREFS
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Cf. A091049, A141836, A141837, A141838, A141839, A141841, A141842.
Sequence in context: A059165 A073718 A061449 this_sequence A065404 A031446 A041492
Adjacent sequences: A141837 A141838 A141839 this_sequence A141841 A141842 A141843
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KEYWORD
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base,more,nonn
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AUTHOR
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Chuck Seggelin (seqfan(AT)plastereddragon.com), Jul 10 2008
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