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A145457
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Exponential transform of C(n,7) = A000580.
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1
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1, 0, 0, 0, 0, 0, 0, 1, 8, 36, 120, 330, 792, 1716, 5148, 57915, 835120, 9354488, 84047184, 638567124, 4256855760, 25607297880, 144863655024, 869425029957, 7081044528888, 83816629147900, 1131047706331400, 14634713798592030
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,9
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COMMENTS
| a(n) is the number of ways of placing n labeled balls into indistinguishable boxes, where in each filled box 7 balls are seen at the top.
a(n) is also the number of forests of labeled rooted trees of height at most 1, with n labels, where each root contains 7 labels.
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LINKS
| N. J. A. Sloane, Transforms
Index entries for sequences related to rooted trees
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MAPLE
| a:= proc(n) option remember; local j; `if` (n=0, 1, add (binomial (n-1, j-1) *binomial(j, 7) *a(n-j), j=1..n)) end: seq (a(n), n=0..30);
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CROSSREFS
| Cf. 7th column of A145460, A143398.
Sequence in context: A008490 A023033 A000580 * A145136 A144901 A054470
Adjacent sequences: A145454 A145455 A145456 * A145458 A145459 A145460
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KEYWORD
| nonn
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AUTHOR
| Alois P. Heinz (heinz(AT)hs-heilbronn.de), Oct 10 2008
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