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Search: id:A096381
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| A096381 |
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Beginning with 2, 7, multiply successive pairs of members and adjoin the result as the next one or two members of the sequence, depending on whether the product is a one- or two-digit number. |
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+0
1
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| 2, 7, 1, 4, 7, 4, 2, 8, 2, 8, 8, 1, 6, 1, 6, 1, 6, 6, 4, 8, 6, 6, 6, 6, 6, 3, 6, 2, 4, 3, 2, 4, 8, 3, 6, 3, 6, 3, 6, 3, 6, 1, 8, 1, 8, 1, 2, 8, 1, 2, 6, 8, 3, 2, 2, 4, 1, 8, 1, 8, 1, 8, 1, 8, 1, 8, 1, 8, 6, 8, 8, 8, 8, 2, 1, 6, 8, 2, 1, 2, 4, 8, 2, 4, 6, 4, 8, 4, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 4, 8, 4, 8, 6, 4
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Larson sets the puzzle of showing that 6 occurs infinitely often in the sequence. It is easy to compose variations on the sequence, e.g., vary a(1) and a(2), or use a base other than 10, or use the product of three successive members instead of 2. I haven't seen the Mathematics Student reference cited in Larson.
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REFERENCES
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Author?, The Mathematics Student, Vol. 26, No. 2, November 1978.
Loren C. Larson, Problem-Solving Through Problems, Springer, 1983, page 8, Problem 1.1.6
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EXAMPLE
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a(1)a(2) = 14, so a(3) = 1 and a(4) = 4
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PROGRAM
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{-Haskell-} a=2:7:concat[(if x*y>9then[x*y`div`10]else[])++[x*y`mod`10]|(x, y)<-a`zip`tail a] (Paul Stoeber (pstoeber(AT)uni-potsdam.de), Oct 08 2005)
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CROSSREFS
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Adjacent sequences: A096378 A096379 A096380 this_sequence A096382 A096383 A096384
Sequence in context: A081705 A065254 A010592 this_sequence A021372 A111714 A060302
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KEYWORD
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base,easy,nonn
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AUTHOR
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Gerry Myerson (gerry(AT)math.mq.edu.au), Aug 04 2004
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