Number of triangles, distinct up to congruence, on a centered hexagonal grid of size n.

Terms

a(0) =0a(1) =4a(2) =34a(3) =134a(4) =379a(5) =866a(6) =1718a(7) =3085a(8) =5149a(9) =8095a(10) =12188a(11) =17664a(12) =24781a(13) =33861a(14) =45269a(15) =59327a(16) =76461a(17) =97017a(18) =121458a(19) =150379a(20) =184053a(21) =223137a(22) =268117a(23) =319578a(24) =378132a(25) =444455a(26) =519178a(27) =602675a(28) =696102a(29) =800051