Number of cubefree self avoiding walks in 2 dimensions of length n.

Terms

a(0) =1a(1) =4a(2) =12a(3) =32a(4) =80a(5) =200a(6) =472a(7) =1136a(8) =2656a(9) =6256a(10) =14584a(11) =34224a(12) =79328a(13) =184904a(14) =427888a(15) =993880a(16) =2294792a(17) =5315464a(18) =12254112a(19) =28321960a(20) =65210608a(21) =150453824a(22) =346041800a(23) =797279272a(24) =1832029592a(25) =4215979016a(26) =9680046176a(27) =22254415152a(28) =51061025160