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Search: id:A122206
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| A122206 |
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Number of sequences b with last index n with b(0) = 1, b(i+1) = b(i)+d where d|b(i). |
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+0
2
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| 1, 1, 2, 5, 17, 66, 307, 1619, 9668, 64112, 469936, 3773496, 32997159, 312542002, 3192352420, 35023164817, 411288004670, 5154265796088, 68746349160704, 973526723323087, 14605620692012861, 231694886107899371
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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b(n) can be as large as 2^n. [From Max Alekseyev (maxale(AT)gmail.com), May 10 2009]
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EXAMPLE
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For n=3, the sequences are 1,2,3,4; 1,2,3,6; 1,2,4,5; 1,2,4,6; and 1,2,4,8. We can't have 1,2,3,5 because the difference (5-3) does not divide 3.
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CROSSREFS
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Cf. A117497, A122205.
Sequence in context: A052539 A008932 A062881 this_sequence A104082 A166474 A054769
Adjacent sequences: A122203 A122204 A122205 this_sequence A122207 A122208 A122209
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KEYWORD
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nonn
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AUTHOR
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Frank Adams-Watters (FrankTAW(AT)Netscape.net), Aug 25 2006
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EXTENSIONS
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a(15)..a(21) from Max Alekseyev (maxale(AT)gmail.com), May 10 2009
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