Number of ways to place 4 points on a triangular grid of side n so that no three of these points are vertices of an equilateral triangle of any orientation.

A240441

Number of ways to place 4 points on a triangular grid of side n so that no three of these points are vertices of an equilateral triangle of any orientation.

Terms

    a(0) =0a(1) =0a(2) =3a(3) =114a(4) =969a(5) =4773a(6) =17415a(7) =52125a(8) =135375a(9) =315675a(10) =676200a(11) =1352085a(12) =2553558a(13) =4595934a(14) =7937874a(15) =13229118a(16) =21369330a(17) =33579450a(18) =51487425a(19) =77229900a(20) =113571975a(21) =164046795a(22) =233117313a(23) =326362179a(24) =450688329a(25) =614572413a(26) =828333870a(27) =1104441975a(28) =1457859900a(29) =1906428300

External references