Number of triangles on a centered hexagonal grid of size n.

Terms

a(0) =0a(1) =32a(2) =900a(3) =7380a(4) =34676a(5) =118044a(6) =325872a(7) =775856a(8) =1653888a(9) =3237984a(10) =5923028a(11) =10249596a(12) =16938588a(13) =26924036a(14) =41393424a(15) =61830480a(16) =90059672a(17) =128293728a(18) =179185500a(19) =245889068a(20) =332107188a(21) =442162836a(22) =581060024a(23) =754545360a(24) =969196896a(25) =1232477192a(26) =1552824900