a(n) = T(n, n-3), T given by A026552. Also a(n) = number of integer strings s(0), ..., s(n) counted by T, such that s(n) = 3.

A026556

a(n) = T(n, n-3), T given by A026552. Also a(n) = number of integer strings s(0), ..., s(n) counted by T, such that s(n) = 3.

Terms

    a(0) =1a(1) =3a(2) =8a(3) =24a(4) =52a(5) =156a(6) =319a(7) =954a(8) =1910a(9) =5696a(10) =11304a(11) =33648a(12) =66514a(13) =197778a(14) =390266a(15) =1159844a(16) =2286996a(17) =6795576a(18) =13397075a(19) =39809076a(20) =78489235a(21) =233262931a(22) =460030947a(23) =1367463642a(24) =2697786052a(25) =8021305890a(26) =15830906756a(27) =47082494816

External references