Number of ways to place 4 points on a triangular grid of side length n so that no three of them are vertices of an equilateral triangle with sides parallel to the grid.

A243213

Number of ways to place 4 points on a triangular grid of side length n so that no three of them are vertices of an equilateral triangle with sides parallel to the grid.

Terms

    a(0) =3a(1) =128a(2) =1062a(3) =5160a(4) =18591a(5) =55113a(6) =142005a(7) =329045a(8) =701160a(9) =1395975a(10) =2626953a(11) =4713723a(12) =8120322a(13) =13503350a(14) =21770766a(15) =34153758a(16) =52292385a(17) =78337890a(18) =115072320a(19) =166048850a(20) =235753353a(21) =329791143a(22) =455099307a(23) =620189115a(24) =835418766a(25) =1113301553a(26) =1468849515a(27) =1919958285

External references