

A094097


Number of divisor chains of length n which begin with n ("anchored" divisor chains).


3



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
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OFFSET

1,8


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.


LINKS

Table of n, a(n) for n=1..44.


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


CROSSREFS

Cf. A067957, A094098, A094099.
Right diagonal of A093323.
Sequence in context: A329457 A081760 A261218 * A145330 A194744 A132669
Adjacent sequences: A094094 A094095 A094096 * A094098 A094099 A094100


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, following a suggestion of R. K. Guy, May 04 2004


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 Christopher Landauer, May 04 2004
a(29)a(37) from Joseph Myers, May 04 2004
a(38) from Jud McCranie, May 07 2004
a(39)a(44) from Joseph Myers, May 21 2004


STATUS

approved



