a(n) = T(n,n-2), T given by A026568. Also a(n) = number of integer strings s(0), ..., s(n) counted by T, such that s(n) = 2.

A026571

a(n) = T(n,n-2), T given by A026568. Also a(n) = number of integer strings s(0), ..., s(n) counted by T, such that s(n) = 2.

Terms

    a(0) =1a(1) =2a(2) =7a(3) =16a(4) =44a(5) =106a(6) =273a(7) =672a(8) =1696a(9) =4214a(10) =10573a(11) =26392a(12) =66151a(13) =165578a(14) =415277a(15) =1041480a(16) =2615004a(17) =6568450a(18) =16512355a(19) =41531360a(20) =104526093a(21) =263206638a(22) =663143211a(23) =1671581968a(24) =4215574482a(25) =10635988422a(26) =26846320149a(27) =67790042264

External references