Number of paths from (0,1) to (n,2), with vertices (i,k) satisfying 0 <= k <= 3, consisting of segments given by the vectors (1,1), (1,2), (1,-1).

A247355

Number of paths from (0,1) to (n,2), with vertices (i,k) satisfying 0 <= k <= 3, consisting of segments given by the vectors (1,1), (1,2), (1,-1).

Terms

    a(0) =0a(1) =1a(2) =2a(3) =3a(4) =8a(5) =12a(6) =28a(7) =49a(8) =100a(9) =191a(10) =370a(11) =724a(12) =1392a(13) =2721a(14) =5254a(15) =10223a(16) =19812a(17) =38456a(18) =74628a(19) =144769a(20) =280984a(21) =545107a(22) =1057862a(23) =2052520a(24) =3982816a(25) =7728177a(26) =14995626a(27) =29097643a(28) =56460416a(29) =109556004

External references