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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 (list; graph; refs; listen; history; text; internal format)
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: A201327 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 Chris Landauer (cal(AT)aero.org), 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

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Last modified November 22 03:20 EST 2019. Contains 329383 sequences. (Running on oeis4.)