A118025 Column 0 of triangle A118024; also, column 0 of the matrix square of A118024 equals this sequence shifted 1 place left.

1, 1, 2, 6, 28, 216, 2864, 66656, 2760896, 205824384, 27886535424, 6924055315968, 3173107641551872, 2700294145104025600, 4289542333320782426112, 12777557344991526923034624, 71652489091220599890081005568

Offset: 0

Author

Paul D. Hanna, Apr 10 2006

Keywords

• nonn

Crossrefs

Cf. A118024.

Formula

a(n) = Sum_{k=0..n-1} 2^(k*(n-1-k))*a(k)*a(n-1-k) for n>0 with a(0)=1.