A223989 Number of 4Xn 0..3 arrays with rows unimodal and columns nondecreasing.
35, 1225, 25410, 358118, 3770722, 31585056, 219861244, 1312747586, 6885325482, 32313530946, 137690265950, 539018300034, 1957451099304, 6647631120056, 21256016741041, 64364748455011, 185491652223781, 510953158157281
Offset: 1
Keywords
Examples
Some solutions for n=3 ..0..0..0....0..1..0....1..1..2....0..2..1....0..0..0....1..2..0....0..2..0 ..1..1..1....0..1..0....1..3..3....0..2..2....2..3..1....2..3..1....0..2..1 ..1..3..3....0..2..0....2..3..3....0..3..2....2..3..1....2..3..1....0..2..1 ..1..3..3....0..3..2....2..3..3....3..3..3....3..3..2....3..3..1....0..3..1
Links
- R. H. Hardin, Table of n, a(n) for n = 1..210
Formula
Empirical: a(n) = (1/2906843957821440000)*n^24 + (11/242236996485120000)*n^23 + (4897/1529252690853888000)*n^22 + (2857/19308746096640000)*n^21 + (973813/198604245565440000)*n^20 + (4751599/38617492193280000)*n^19 + (31125329/12804747411456000)*n^18 + (103519301/2667655710720000)*n^17 + (2190105457/4304116776960000)*n^16 + (4631351591/836911595520000)*n^15 + (151304213363/3012881743872000)*n^14 + (22821847439/59779399680000)*n^13 + (807436276336499/331416991825920000)*n^12 + (2978829718733/228248616960000)*n^11 + (12597307863407/215205838848000)*n^10 + (15260090056063/69742632960000)*n^9 + (21685072444447303/32011868528640000)*n^8 + (72957402495727/42343741440000)*n^7 + (108238697285043737/30411275102208000)*n^6 + (24731243901001117/4223788208640000)*n^5 + (1127736066113539/150849578880000)*n^4 + (8436170802181/1173274502400)*n^3 + (193928573189123/37104806138400)*n^2 + (1070454625/535422888)*n + 1
Comments