67108288

Appears in sequences

• If an array is made of columns of -nacci sequences, fibo-, tribo- etc. all starting w. 1,1,2 etc, the NW to SE diagonals can be extended by computation. The above is diagonal 10. See A159741 for details.at n=17A159747
• a(n) = 2^(n+1) - (n-1)^2.at n=25A243860