A094097 Number of divisor chains of length n which begin with n ("anchored" divisor chains).

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

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