26843

Appears in sequences

• a(0)=3; thereafter, a(n) = A002426(n+1) + Fibonacci(n-1)*(Fibonacci(n-1) + 1).at n=10A059728
• Irregular triangle read by rows: T(n,k) is the number of regions between the free polyominoes, with n cells and width k, and their bounding boxes, n >= 1, 1 <= k <= ceiling(n/2).at n=33A380283