Number of chiral pairs of rows of n colors with exactly 4 different colors.

A305624

Number of chiral pairs of rows of n colors with exactly 4 different colors.

Terms

    a(0) =0a(1) =0a(2) =0a(3) =12a(4) =120a(5) =780a(6) =4188a(7) =20400a(8) =93120a(9) =409140a(10) =1748220a(11) =7337232a(12) =30386160a(13) =124696740a(14) =508250988a(15) =2061566400a(16) =8331954240a(17) =33585590580a(18) =135115594140a(19) =542784981552

External references