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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A092441 Sequence arising from enumeration of domino tilings of Aztec Pillow-like regions. 2
1, 10, 65, 346, 1637, 7218, 30529, 126034, 513125, 2072698, 8335505, 33439914, 133972165, 536346850, 2146369793, 8587575586, 34354757957, 137428468074, 549733794193, 2198977118650, 8795996553701, 35184170762770 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

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..21.

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 (11,-47,101,-116,68,-16).

FORMULA

a(n) = 2^(2n+3)-2^(n+2)-2(n+2)(2^(n+1)-1)+(n+1)^2.

G.f.: -(8*x^4-2*x^2+x-1)/((x-1)^3*(2*x-1)^2*(4*x-1)). [Colin Barker, Nov 22 2012]

EXAMPLE

a(3)=2^9-2^5-10(2^4-1)+4^2=346.

CROSSREFS

Cf. A092437-A092443.

Sequence in context: A023009 A169797 A073381 * A022638 A003519 A056280

Adjacent sequences:  A092438 A092439 A092440 * A092442 A092443 A092444

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 16 20:34 EDT 2018. Contains 316275 sequences. (Running on oeis4.)