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A094097
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Number of divisor chains of length n which begin with n ("anchored" divisor chains).
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2
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1, 1, 1, 1, 1, 1, 1, 5, 4, 3, 2, 8, 4, 6, 47, 44, 6, 37, 6, 166, 462, 232, 372, 2130, 1589, 9093, 20896, 20314, 4118, 32367, 12815, 167796, 130528, 59173, 1942045, 2607312, 163775, 1297794, 18340336, 22304602, 5065878, 21005347, 3607762, 129164605
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,8
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COMMENTS
| A divisor chain of length n is an arrangement of 1..n such that each term is a divisor of the sum of the preceding terms.
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EXAMPLE
| Examples of divisor chains of lengths 1 through 8:
1
2 1
3 1 2
4 2 3 1
5 1 2 4 3
6 2 4 3 5 1
7 1 2 5 3 6 4
8 2 5 3 6 4 7 1
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CROSSREFS
| Cf. A067957, A094098, A094099.
Sequence in context: A003561 A201327 A081760 * A145330 A194744 A132669
Adjacent sequences: A094094 A094095 A094096 * A094098 A094099 A094100
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), following a suggestion of R. K. Guy, May 04 2004
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EXTENSIONS
| a(1)-a(9) from R. K. Guy and Paul Vaderlind, a(10)-a(19) from Ed Clark, Jr. and Chuck Seggelin, a(20)-a(28) from Chris Landauer (cal(AT)aero.org), May 04, 2004.
a(29)-a(37) from Joseph S. Myers (jsm(AT)polyomino.org.uk), May 04, 2004
a(38) from Jud McCranie (JudMcCranie(AT)ugaalum.uga.edu), May 07 2004
a(39)-a(44) from Joseph Myers (jsm(AT)polyomino.org.uk), May 21 2004
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