login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A092442 Sequence arising from enumeration of domino tilings of Aztec Pillow-like regions. 1
0, 1, 5, 19, 59, 161, 405, 967, 2231, 5029, 11153, 24443, 53091, 114505, 245549, 524047, 1113839, 2358989, 4980393, 10485379, 22019675, 46136881, 96468485, 201326039, 419429799, 872414581, 1811938625, 3758095627, 7784627411 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Differences give A066368.

REFERENCES

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 13).

LINKS

Table of n, a(n) for n=0..28.

J. Propp, Publications and Preprints

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

Index entries for linear recurrences with constant coefficients, signature (7,-19,25,-16,4).

FORMULA

a(n)=(n+1)(2^n-1)-n^2.

G.f.:(x*(4*x^3-3*x^2+2*x-1))/((2*x-1)^2*(x-1)^3) [From Maksym Voznyy (voznyy(AT)mail.ru), Jul 26 2009]

EXAMPLE

a(3)=4(2^3-1)-3^2=19.

CROSSREFS

Cf. A092437-A092443.

Sequence in context: A029861 A224034 A107179 * A135266 A124123 A189714

Adjacent sequences:  A092439 A092440 A092441 * A092443 A092444 A092445

KEYWORD

easy,nonn

AUTHOR

Christopher Hanusa (chanusa(AT)math.washington.edu), Mar 24 2004

STATUS

approved

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 February 16 03:15 EST 2019. Contains 320140 sequences. (Running on oeis4.)