|
Search: id:A092491
|
|
| |
|
| 0, 0, 0, 0, 1, 6, 25, 93, 333, 1172, 4083, 14137, 48778, 167981, 577874, 1986747, 6828120, 23462470, 80611581, 276944893, 951422603, 3268470411, 11228209786, 38572124196, 132505812826, 455192771711, 1563706508759, 5371738013650
(list; graph; listen)
|
|
|
OFFSET
|
1,6
|
|
|
COMMENT
|
A recurrence relation follows in a straightforward manner from the above formula and the recurrence relation for A058094.
|
|
REFERENCES
|
Z. Stankova and J. West, Explicit enumeration of 321, hexagon-avoiding permutations, Discrete Math., 280 (2004), 165-189.
|
|
MAPLE
|
b[1]:=1:b[2]:=2:b[3]:=5:b[4]:=14:b[5]:=42:b[6]:=132: for n from 6 to 34 do b[n+1]:=6*b[n]-11*b[n-1]+9*b[n-2]-4*b[n-3]-4*b[n-4]+b[n-5] od: a[1]:=0:a[2]:=0:a[3]:=0:a[4]:=0: for n from 5 to 34 do a[n]:=2*b[n-2]-5*b[n-3]+b[n-4]+a[n-1] od: seq(a[n], n=1..34); (Deutsch)
|
|
CROSSREFS
|
Cf. A058094, A092489-A092492.
Sequence in context: A000392 A099948 A143815 this_sequence A112308 A034336 A092184
Adjacent sequences: A092488 A092489 A092490 this_sequence A092492 A092493 A092494
|
|
KEYWORD
|
nonn,easy
|
|
AUTHOR
|
N. J. A. Sloane (njas(AT)research.att.com), Apr 04 2004
|
|
EXTENSIONS
|
Edited by Emeric Deutsch (deutsch(AT)duke.poly.edu), Apr 12 2005
|
|
|
Search completed in 0.002 seconds
|
