Nonnegative walks of length n on the x-axis starting at the origin using steps {1,-1} and visiting no point more than twice.

A212584

Nonnegative walks of length n on the x-axis starting at the origin using steps {1,-1} and visiting no point more than twice.

Terms

    a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =6a(6) =9a(7) =12a(8) =18a(9) =24a(10) =34a(11) =46a(12) =65a(13) =89a(14) =124a(15) =170a(16) =236a(17) =325a(18) =450a(19) =620a(20) =857a(21) =1182a(22) =1633a(23) =2253a(24) =3111a(25) =4293a(26) =5927a(27) =8180a(28) =11292a(29) =15585

External references