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A093323 Triangle read by rows giving number of divisor chains of length n beginning with k (1 <= k <= n). 1
1, 0, 1, 0, 1, 1, 0, 0, 1, 1, 0, 0, 1, 2, 1, 0, 0, 0, 2, 2, 1, 0, 0, 0, 2, 3, 1, 1, 0, 0, 0, 0, 1, 0, 1, 5, 0, 0, 0, 0, 1, 3, 4, 12, 4, 0, 0, 0, 0, 0, 4, 5, 7, 3, 3, 0, 0, 0, 0, 0, 4, 7, 9, 3, 4, 2, 0, 0, 0, 1, 0, 0, 2, 5, 4, 8, 11, 8, 0, 0, 0, 1, 0, 0, 2, 7, 11, 12, 19, 11, 4, 0, 0, 0, 0, 0, 0 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,14

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..97.

EXAMPLE

Triangle begins:

1

0 1

0 1 1

0 0 1 1

0 0 1 2 1

0 0 0 2 2 1

0 0 0 2 3 1 1

0 0 0 0 1 0 1 5

0 0 0 0 1 3 4 12 4

0 0 0 0 0 4 5 7 3 3

0 0 0 0 0 4 7 9 3 4 2

0 0 0 1 0 0 2 5 4 8 11 8

0 0 0 1 0 0 2 7 11 12 19 11 4

0 0 0 0 0 0 0 4 12 4 14 7 8 6

0 0 0 1 0 2 3 14 32 42 64 41 77 63 47

0 0 0 1 0 0 0 0 16 34 39 26 20 24 31 44

0 0 0 1 0 0 0 0 16 44 55 27 34 31 42 56 6

0 0 0 0 0 2 3 2 2 21 13 20 19 31 51 70 76 37

0 0 0 0 0 4 3 3 7 21 17 24 25 34 54 91 113 49 6

0 0 0 0 0 2 0 8 17 12 31 41 43 91 60 121 223 144 360 166

0 0 0 0 0 7 0 20 31 26 57 197 314 383 283 706 938 473 969 454 462

0 0 0 0 0 6 0 17 18 21 0 124 131 220 148 445 538 232 443 222 423 232

0 0 0 0 0 6 0 17 22 29 9 138 164 279 188 520 640 309 616 302 521 357 372

0 0 0 6 0 6 0 44 76 219 86 155 314 545 389 1354 1296 819 727 1246 1959 2619 6247 2130

0 0 0 8 0 11 7 60 112 257 102 273 323 1519 579 2388 2828 1600 2193 2535 3532 3955 9554 3155 1589

0 0 0 3 5 14 15 80 53 139 34 556 453 3063 1160 3194 1739 1756 2015 3648 5311 2903 7496 4084 6061 9093

CROSSREFS

Cf. A094097 (right diagonal).

Sequence in context: A004198 A324351 A116402 * A106278 A177517 A227819

Adjacent sequences:  A093320 A093321 A093322 * A093324 A093325 A093326

KEYWORD

tabl,nonn

AUTHOR

Eugene McDonnell (eemcd(AT)mac.com), May 11 2004

STATUS

approved

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Last modified July 21 03:22 EDT 2019. Contains 325189 sequences. (Running on oeis4.)