A368809 Number of 4 X n binary arrays with a path of adjacent 1's from top row to bottom row using only left, right, and downward steps.
1, 41, 1041, 22193, 433801, 8057625, 144762849, 2540882465, 43840779353, 746649798473, 12587443678705, 210491254232465, 3496816762316713, 57778098654714361, 950391251581267073, 15574198350636963201, 254405750326548970361, 4144508602760970898729, 67361936661916258817937
Offset: 1
Examples
For example, here is one such 4 X 4 array:
0001
1111
1010
1100
The following 4 X 5 array is a non-example, as there is no path using only left, right, and downward steps:
10000
10111
11101
00001
Links
- Index entries for linear recurrences with constant coefficients, signature (36,-413,1642,-2536,1152).
Formula
G.f.: x*(1 + 5*x - 22*x^2 + 8*x^3)/((1 - 16*x)*(1 - 20*x + 93*x^2 - 154*x^3 + 72*x^4)). - Pontus von Brömssen, Feb 05 2025
Extensions
More terms from Pontus von Brömssen, Feb 05 2025
Comments