Triangle T(n, k) = f(k) for k < n+1, otherwise 0, where f(k) = f(k-1) + k^(k-2)*f(k-2) with f(0) = 0 and f(1) = 1, read by rows.
A136680
Triangle T(n, k) = f(k) for k < n+1, otherwise 0, where f(k) = f(k-1) + k^(k-2)*f(k-2) with f(0) = 0 and f(1) = 1, read by rows.
Terms
- a(0) =1a(1) =1a(2) =1a(3) =1a(4) =1a(5) =4a(6) =1a(7) =1a(8) =4a(9) =20a(10) =1a(11) =1a(12) =4a(13) =20a(14) =520a(15) =1a(16) =1a(17) =4a(18) =20a(19) =520a(20) =26440a(21) =1a(22) =1a(23) =4a(24) =20a(25) =520a(26) =26440a(27) =8766080a(28) =1a(29) =1
External references
- oeis: A136680