Number of 4-cycles in the n-polygon diagonal intersection graph.

Terms

a(0) =0a(1) =5a(2) =10a(3) =24a(4) =35a(5) =80a(6) =90a(7) =170a(8) =220a(9) =420a(10) =364a(11) =644a(12) =780a(13) =1120a(14) =1139a(15) =1854a(16) =1748a(17) =2580a(18) =2898a(19) =3916a(20) =3450a(21) =6072a(22) =5350a(23) =7046a(24) =7398a(25) =10024a(26) =10063a(27) =14250a(28) =13795a(29) =16608