A223845 Number of nX3 0..3 arrays with rows and columns unimodal.
50, 2500, 64660, 1006318, 10804883, 87613063, 570145144, 3107412546, 14632983606, 60951077586, 228682697934, 784020062496, 2484771896660, 7348846431262, 20442258040721, 53835488429681, 134975315832464
Offset: 1
Keywords
Examples
Some solutions for n=3 ..3..0..0....1..0..0....0..1..0....3..1..0....1..2..1....0..0..3....2..3..2 ..3..3..2....1..3..2....3..3..3....3..2..1....0..2..3....2..2..1....0..3..2 ..3..2..1....3..1..1....0..2..2....0..1..3....0..3..3....3..1..0....0..2..3
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (89/169374965760)*n^18 + (811/30536352000)*n^17 + (2373533/3487131648000)*n^16 + (699851/62270208000)*n^15 + (11519407/87178291200)*n^14 + (51637/44352000)*n^13 + (7243453/912384000)*n^12 + (306562541/7185024000)*n^11 + (148370021/812851200)*n^10 + (33909163/54432000)*n^9 + (455467827113/268240896000)*n^8 + (5892168577/1596672000)*n^7 + (80009607001/12454041600)*n^6 + (31958071429/3592512000)*n^5 + (2175260234977/217945728000)*n^4 + (5539161569/648648000)*n^3 + (6387435643/1029188160)*n^2 + (637969/235620)*n + 1
Comments