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Search: id:A032262
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| A032262 |
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Number of ways to partition n labeled elements into pie slices allowing the pie to be turned over. |
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+0
2
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| 1, 2, 5, 17, 83, 557, 4715, 47357, 545963, 7087517, 102248075, 1622633597, 28091569643, 526858352477, 10641342978635, 230283190994237, 5315654682014123, 130370767029201437, 3385534663256976395
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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C. G. Bower, Transforms (2)
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FORMULA
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a(n) = 2^(n-2) + A000670(n-1) for n >= 2. - N. J. A. Sloane (njas(AT)research.att.com), Jan 17 2008
a(n) = 2^(n-1) + Sum_{k >= 3} Stirling_2(n,k)*(k-1)!/2. - N. J. A. Sloane (njas(AT)research.att.com), Jan 17 2008
"DIJ" (bracelet, indistinct, labeled) transform of 1, 1, 1, 1... (see Bower link).
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EXAMPLE
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For n = 4 we have the following "pies":
. 1
./ \
2 . 3 . 12 .. 12 . 123 .1234
.\ / .. / \ .(..)..(..)
. 4 .. 3--4 . 34 .. 4
.(3)....(6)...(3)..(4)...(1) Total a(4) = 17
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CROSSREFS
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Row sums of triangle A133800.
Sequence in context: A076322 A098540 A079574 this_sequence A144259 A079805 A162038
Adjacent sequences: A032259 A032260 A032261 this_sequence A032263 A032264 A032265
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KEYWORD
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nonn
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AUTHOR
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Christian G. Bower (bowerc(AT)usa.net)
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EXTENSIONS
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Edited by N. J. A. Sloane (njas(AT)research.att.com), Jan 17 2008
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