Number of n-step two-sided prudent self-avoiding walks ending at the northeast corner of their box.

Terms

a(0) =1a(1) =2a(2) =4a(3) =10a(4) =24a(5) =58a(6) =140a(7) =340a(8) =828a(9) =2022a(10) =4948a(11) =12130a(12) =29780a(13) =73202a(14) =180124a(15) =443614a(16) =1093376a(17) =2696622a(18) =6654568a(19) =16430016a(20) =40583388a(21) =100283298a(22) =247890520a(23) =612951190a(24) =1516046060a(25) =3750655206a(26) =9281098840a(27) =22970992024a(28) =56864328080a(29) =140790241078