%I #34 Feb 08 2024 16:47:00
%S 0,1,6,22,66,151,312,564,984,1601,2478,3622,5242,7271,9856,13124,
%T 17296,22229,28286,35306,43850,53891,65520,78624,94272,111977,131990,
%U 154514,180290,208611,240840,276032,315720,359497,407470,460078,519018,582447,651232,725820,808416
%N Number of rhombi on an n X n grid (or geoboard).
%H Ray Chandler, <a href="/A189418/b189418.txt">Table of n, a(n) for n = 1..1000</a> (first 92 terms from R. H. Hardin)
%H Nathaniel Johnston, <a href="/A189418/a189418.c.txt">C program for computing terms</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/Rhombus.html">Rhombus</a>
%Y Cf. A181947, A189413, A189414.
%K nonn
%O 1,3
%A _Martin Renner_, Apr 21 2011
%E a(6)-a(28) from _Nathaniel Johnston_, Apr 23 2011
%E Terms beyond a(28) by _R. H. Hardin_, May 04 2011