The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.



Please make a donation to keep the OEIS running. We are now in our 56th year. In the past year we added 10000 new sequences and reached almost 9000 citations (which often say "discovered thanks to the OEIS").
Other ways to donate

(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A071091 Number of tilings by lozenges of hexagon with sides 2n, 2n+3, 2n, 2n+3, 2n, 2n+3 and middle triangle in each edge removed. 0
1, 6272, 23763455716, 55031753041200000000, 73940670068249096897010952625900 (list; graph; refs; listen; history; text; internal format)



J. Propp, Enumeration of matchings: problems and progress, pp. 255-291 in L. J. Billera et al., eds, New Perspectives in Algebraic Combinatorics, Cambridge, 1999 (see Problem 2).


Table of n, a(n) for n=1..5.

M. Ciucu et al., Enumeration of lozenge tilings of hexagons with a central triangular hole, arXiv:math/9912053 [math.CO], 1999.

J. Propp, Update on Enumeration of Matchings, 2009.

J. Propp, Enumeration of matchings: problems and progress, in L. J. Billera et al. (eds.), New Perspectives in Algebraic Combinatorics


Sequence in context: A234440 A254635 A189655 * A209826 A107582 A213869

Adjacent sequences:  A071088 A071089 A071090 * A071092 A071093 A071094




N. J. A. Sloane, May 28 2002



Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 26 12:37 EST 2020. Contains 338639 sequences. (Running on oeis4.)