Number of 4-way intersections in the interior of a regular 6n-gon.

Terms

a(0) =0a(1) =12a(2) =54a(3) =264a(4) =420a(5) =396a(6) =1134a(7) =1200a(8) =1296a(9) =3780a(10) =2310a(11) =2520a(12) =3276a(13) =3612a(14) =4050a(15) =5088a(16) =5712a(17) =5724a(18) =7182a(19) =11400a(20) =9072a(21) =9372a(22) =10626a(23) =11088a(24) =12600a(25) =13260a(26) =14094a(27) =15960a(28) =17052a(29) =23220