

A274582


Number of ways to remove n oranges from an infinite stack of oranges whose mth layer is an m X m square.


6



1, 1, 4, 10, 24, 51, 109, 222, 452, 890, 1732, 3298, 6204, 11470, 20970, 37842, 67572, 119368, 208943, 362389, 623438, 1064061, 1802976, 3033711, 5071418, 8424788, 13913192, 22847028, 37315678, 60631940, 98030644, 157743554, 252671288, 402944731, 639871871, 1011956958
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OFFSET

0,3


COMMENTS

This problem was stated in this fashion by R. Kenyon in the Domino Forum (domino@listserv.uml.edu).


LINKS

Suresh Govindarajan, Table of n, a(n) for n = 0..60
S. Govindarajan, A. J. Guttmann and V. Subramanyan, On a squareice analogue of plane partitions, arXiv:1607.01890 [condmat.statmech], 2016.


EXAMPLE

a(1)=1 as only the orange in the top layer can be removed. a(2)=4 as there are four oranges in the second layer and any one of them can be removed.


CROSSREFS

Cf. A274594, A274596, A274597, A274598, A274599.
Sequence in context: A128516 A022569 A093831 * A052365 A107659 A162588
Adjacent sequences: A274579 A274580 A274581 * A274583 A274584 A274585


KEYWORD

nonn,hard


AUTHOR

Suresh Govindarajan, Jun 30 2016


STATUS

approved



