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Search: id:A006957
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| A006957 |
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Self-convolution of numbers of preferential arrangements. |
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1
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| 1, 2, 7, 32, 185, 1310, 11067, 109148, 1234045, 15752858, 224169407, 3518636504, 60381131265, 1124390692886, 22577494959427, 486212633129300, 11177317486573445, 273173247028616594, 7072436847620016327
(list; graph; listen)
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OFFSET
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0,2
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MAPLE
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f:= proc(n) option remember; `if`(n<=1, 1, add (binomial (n, k) *f(n-k), k=1..n)) end: a:= n-> add (f(k) *f(n-k), k=0..n): seq (a(n), n=0..25); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Feb 02 2009]
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CROSSREFS
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Cf. A000670.
Sequence in context: A000153 A006154 A000987 this_sequence A079265 A112006 A067551
Adjacent sequences: A006954 A006955 A006956 this_sequence A006958 A006959 A006960
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KEYWORD
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nonn
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AUTHOR
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N. J. A. Sloane (njas(AT)research.att.com).
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EXTENSIONS
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More terms from Alois P. Heinz (heinz(AT)hs-heilbronn.de), Feb 02 2009
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