A223802 Number of 3Xn 0..3 arrays with rows and antidiagonals unimodal

64, 4096, 110116, 1658703, 16979881, 131295500, 818316500, 4293683039, 19561009057, 79169569680, 289707943960, 971844411710, 3021916484046, 8789182733640, 24090737306249, 62620436201529, 155188103218258

Offset

1,1

Comments

Row 3 of A223801

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 + (94651/130767436800)*n^16 + (32953/2554051500)*n^15 + (353321/2134978560)*n^14 + (42487607/26687232000)*n^13 + (2427919/205286400)*n^12 + (329331899/4790016000)*n^11 + (2304632003/7315660800)*n^10 + (10342060619/9144576000)*n^9 + (4533016361/1437004800)*n^8 + (13748687149/2052864000)*n^7 + (50457321263/4670265600)*n^6 + (22295176297/1796256000)*n^5 + (1377479947/136216080)*n^4 + (30053444821/9081072000)*n^3 + (2978057767/367567200)*n^2 + (16725/2431)*n + 1

Example

Some solutions for n=3
..2..2..0....2..3..3....3..1..0....2..0..0....0..3..1....2..1..0....1..2..2
..3..1..0....2..2..1....2..1..1....0..0..3....3..2..1....1..3..1....1..2..0
..1..1..3....1..2..0....3..3..0....1..3..1....2..2..0....1..3..1....3..1..0

Crossrefs

Sequence in context: A223877 A188907 A189108 * A297379 A283862 A223567

Adjacent sequences: A223799 A223800 A223801 * A223803 A223804 A223805

Keyword

nonn

Author

R. H. Hardin Mar 27 2013

Status

approved