A387267 Number of dissections of a convex n-gon into quadrilaterals and pentagons by strictly disjoint diagonals.
0, 1, 1, 3, 7, 8, 19, 31, 47, 87, 135, 219, 371, 579, 947, 1535, 2423, 3919, 6239, 9891, 15803, 24987, 39563, 62663, 98751, 155815, 245431, 385771, 606467, 951795, 1492323, 2338703, 3660551, 5725951, 8950543, 13978931, 21820235, 34037067, 53059643, 82670167
Offset: 3
Links
- Muhammed Sefa Saydam, Table of n, a(n) for n = 3..100
Formula
a(n) = T(n-3) + Sum_{i=1..n-8} T(i)*( T(n-i-4) + T(n-i-7) ) + Sum_{i=n-7..n-5} T(i)*( 1 + T(n-i-4) ) for n >= 9 and T(n) = A159284(n).
Comments