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A032262 Number of ways to partition n labeled elements into pie slices allowing the pie to be turned over. 1
1, 2, 5, 17, 83, 557, 4715, 47357, 545963, 7087517, 102248075, 1622633597, 28091569643, 526858352477, 10641342978635, 230283190994237, 5315654682014123, 130370767029201437, 3385534663256976395 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..19.

C. G. Bower, Transforms (2)

FORMULA

a(n) = 2^(n-2) + A000670(n-1) for n >= 2. - N. J. A. Sloane, Jan 17 2008

a(n) = 2^(n-1) + Sum_{k >= 3} Stirling_2(n,k)*(k-1)!/2. - N. J. A. Sloane, Jan 17 2008

"DIJ" (bracelet, indistinct, labeled) transform of 1, 1, 1, 1... (see Bower link).

EXAMPLE

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

CROSSREFS

Row sums of triangle A133800.

Sequence in context: A076322 A098540 A079574 * A144259 A191799 A079805

Adjacent sequences:  A032259 A032260 A032261 * A032263 A032264 A032265

KEYWORD

nonn

AUTHOR

Christian G. Bower

EXTENSIONS

Edited by N. J. A. Sloane, Jan 17 2008

STATUS

approved

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Last modified February 23 09:40 EST 2018. Contains 299509 sequences. (Running on oeis4.)