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

Terms

a(0) =0a(1) =12a(2) =216a(3) =1104a(4) =3708a(5) =9396a(6) =20304a(7) =38868a(8) =68364a(9) =112632a(10) =176076a(11) =263832a(12) =381924a(13) =536424a(14) =735240a(15) =985896a(16) =1296540a(17) =1676508a(18) =2137392a(19) =2689248a(20) =3344244a(21) =4114020