A189418 Number of rhombi on an n X n grid (or geoboard).

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

Offset

1,3

Links

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. A181947, A189413, A189414.

Sequence in context: A347435 A003469 A364415 * 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