|
Search: id:A105072
|
|
|
| A105072 |
|
Number of permutations on [n] whose local maxima are in ascending order. |
|
+0
1
|
|
| 1, 2, 5, 16, 63, 290, 1511, 8756, 55761, 386394, 2889181, 23152104, 197714479, 1790887562, 17136276943, 172602398812, 1824364931681, 20179983080754, 233031648587509, 2803140527987776, 35055393201882847, 454955691827090802
(list; graph; listen)
|
|
|
OFFSET
|
1,2
|
|
|
REFERENCES
|
Goulden & Jackson, Enumerative Combinatorics section 5.2.
|
|
FORMULA
|
E.g.f.: exp((6x-1+exp(2x))/4)
|
|
EXAMPLE
|
a(3) = 5 since we have 123, 321, 231, 132 and 213 but not 312.
|
|
MATHEMATICA
|
Range[0, 21]! CoefficientList[ Series[E^((6x - 1 + E^(2x))/4), {x, 0, 21}], x] (from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005)
|
|
CROSSREFS
|
Sequence in context: A007124 A112951 A124470 this_sequence A022494 A136127 A111004
Adjacent sequences: A105069 A105070 A105071 this_sequence A105073 A105074 A105075
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Louis Shapiro (lshapiro(AT)howard.edu), Apr 06 2005
|
|
EXTENSIONS
|
More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Apr 09 2005
|
|
|
Search completed in 0.002 seconds
|
