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A189418 Number of rhombi on an n X n grid (or geoboard). 6
0, 1, 6, 22, 66, 151, 312, 564, 984, 1601, 2478, 3622, 5242, 7271, 9856, 13124, 17296, 22229, 28286, 35306, 43850, 53891, 65520, 78624, 94272, 111977, 131990, 154514, 180290, 208611, 240840, 276032, 315720, 359497, 407470, 460078, 519018, 582447, 651232, 725820, 808416 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

R. H. Hardin, Ray Chandler, Table of n, a(n) for n = 1..1000 (first 92 terms from R. H. Hardin)

Nathaniel Johnston, C program for computing terms

Eric Weisstein's World of Mathematics, Rhombus

CROSSREFS

Cf. A189413, A189414.

Sequence in context: A099855 A347435 A003469 * A027992 A271389 A353703

Adjacent sequences: A189415 A189416 A189417 * A189419 A189420 A189421

KEYWORD

nonn

AUTHOR

Martin Renner, Apr 21 2011

EXTENSIONS

a(6)-a(28) from Nathaniel Johnston, Apr 23 2011

Terms beyond a(28) by R. H. Hardin, May 04 2011

STATUS

approved

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Last modified December 10 02:09 EST 2022. Contains 358712 sequences. (Running on oeis4.)