[go: up one dir, main page]
login
The OEIS is supported by the many generous donors to the OEIS Foundation.
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A230556
Number of involutions avoiding the pattern 4231.
7
1, 1, 2, 4, 9, 21, 51, 128, 327, 858, 2272, 6146, 16716, 46246, 128414, 361493, 1020506, 2913060, 8335405, 24067930, 69646035
(list; graph; refs; listen; history; text; internal format)
OFFSET
0,3
LINKS
Table of n, a(n) for n=0..20.
Miklós Bóna, Cheyne Homberger, Jay Pantone, and Vince Vatter, Pattern-avoiding involutions: exact and asymptotic enumeration, arxiv:1310.7003, 2013.
EXAMPLE
Of the 26 involutions of length 5, only 53241, 42315, 52431, 52341, and 15342 contain the pattern 4231, so a(5) = 21.
CROSSREFS
Cf. A000085, A001006, A121704, A230551-A230555.
Sequence in context: A001006 A086246 A247100 * A027057 A333105 A148071
Adjacent sequences: A230553 A230554 A230555 * A230557 A230558 A230559
KEYWORD
nonn,more
AUTHOR
Cheyne Homberger, Oct 23 2013
STATUS
approved

Lookup Welcome Wiki Register Music Plot 2 Demos Index WebCam Contribute Format Style Sheet Transforms Superseeker Recents
The OEIS Community
Maintained by The OEIS Foundation Inc.
Last modified November 7 12:11 EST 2024. Contains 377535 sequences.
License Agreements, Terms of Use, Privacy Policy