Triangle, read by rows, T(n, k) = binomial(n, k) for n < 2 and binomial(n, k) + 3^(n-1)*binomial(n-2, k -1) otherwise.

A146987

Triangle, read by rows, T(n, k) = binomial(n, k) for n < 2 and binomial(n, k) + 3^(n-1)*binomial(n-2, k -1) otherwise.

Terms

    a(0) =1a(1) =1a(2) =1a(3) =1a(4) =5a(5) =1a(6) =1a(7) =12a(8) =12a(9) =1a(10) =1a(11) =31a(12) =60a(13) =31a(14) =1a(15) =1a(16) =86a(17) =253a(18) =253a(19) =86a(20) =1a(21) =1a(22) =249a(23) =987a(24) =1478a(25) =987a(26) =249a(27) =1a(28) =1a(29) =736

External references