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A141841 a(n) is the 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 7 so that each interpretation is base 8. Terms already fully reduced (i.e., single digits) are excluded. 6
17, 57, 71, 107, 4647, 11047, 25447, 61547, 170153, 115751335, 671434647, 5001243627, 45206165753 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
It is sometimes possible to compute additional terms by taking the last term, treating it as base 10 and converting to base 8. This may create a term minimally interpretable as base 8 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 produces the value 5001243627 which is minimally interpretable as base 8.
LINKS
EXAMPLE
a(3) = 71 because 71 is the first number that can produce a sequence of three terms by repeated interpretation as a base 8 number: [71] (base-8) --> [57] (base-8) --> [47] (base-8) --> [39]. Since 39 cannot be minimally interpreted as a base 8 number, the sequence terminates with 47. a(1) = 17 because 17 is the first number that can be reduced once, yielding no further terms minimally interpretable as base 8.
CROSSREFS
Sequence in context: A290763 A253417 A117390 * A146682 A146650 A147131
KEYWORD
base,more,nonn
AUTHOR
Chuck Seggelin (seqfan(AT)plastereddragon.com), Jul 10 2008
EXTENSIONS
a(12)-a(13) from Giovanni Resta, Feb 23 2013
STATUS
approved

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Last modified March 29 08:00 EDT 2024. Contains 371265 sequences. (Running on oeis4.)