a(n) = T(n, n-4), T given by A026552. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=4.

A026557

a(n) = T(n, n-4), T given by A026552. Also a(n) = number of integer strings s(0),...,s(n) counted by T, such that s(n)=4.

Terms

    a(0) =1a(1) =3a(2) =12a(3) =28a(4) =93a(5) =201a(6) =631a(7) =1316a(8) =4037a(9) =8259a(10) =25052a(11) =50680a(12) =152782a(13) =306958a(14) =921982a(15) =1844304a(16) =5526849a(17) =11024331a(18) =32987492a(19) =65675764a(20) =196323853a(21) =390374193a(22) =1166171943a(23) =2316881892a(24) =6918228187a(25) =13737041045a(26) =41007165500

External references