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

Terms

a(0) =1a(1) =2a(2) =4a(3) =9a(4) =20a(5) =46a(6) =105a(7) =244a(8) =567a(9) =1328a(10) =3114a(11) =7334a(12) =17301a(13) =40925a(14) =96955a(15) =230128a(16) =546942a(17) =1301721a(18) =3101513a(19) =7397751a(20) =17661413a(21) =42201765a(22) =100918554a(23) =241504437a(24) =578312697a(25) =1385684687a(26) =3322065246a(27) =7968514308a(28) =19122960036a(29) =45912141148