a(n) = T(n, n-1), T given by A026519. Also a(n) = number of integer strings s(0), ..., s(n), counted by T, such that s(n) = 1.

A026521

a(n) = T(n, n-1), T given by A026519. Also a(n) = number of integer strings s(0), ..., s(n), counted by T, such that s(n) = 1.

Terms

    a(0) =1a(1) =1a(2) =4a(3) =6a(4) =19a(5) =33a(6) =98a(7) =180a(8) =526a(9) =990a(10) =2887a(11) =5502a(12) =16073a(13) =30863a(14) =90386a(15) =174456a(16) =512128a(17) =992304a(18) =2918954a(19) =5673140a(20) =16716998a(21) =32571858a(22) =96119927a(23) =187675644a(24) =554524660a(25) =1084649644a(26) =3208254571a(27) =6284986554a(28) =18607536319a(29) =36501029265

External references