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

A026520

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

Terms

    a(0) =1a(1) =1a(2) =2a(3) =4a(4) =8a(5) =20a(6) =38a(7) =104a(8) =196a(9) =556a(10) =1052a(11) =3032a(12) =5774a(13) =16778a(14) =32146a(15) =93872a(16) =180772a(17) =529684a(18) =1024256a(19) =3008864a(20) =5837908a(21) =17184188a(22) =33433996a(23) =98577712a(24) =192239854a(25) =567591142a(26) =1109049320a(27) =3278348608a(28) =6416509142a(29) =18986482250

External references