A227639 Number of nX4 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X5 binary array having determinant equal to one, with rows and columns of the latter in nondecreasing lexicographic order

4, 23, 127, 667, 3202, 13740, 53575, 192191, 640831, 2002960, 5909556, 16555375, 44257697, 113385871, 279415526, 664438386, 1528929898, 3412860357, 7406164606, 15655003700, 32288642035, 65081639197, 128377414029, 248137470904

Offset

1,1

Comments

Column 4 of A227641

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = (1/2534272925184000)*n^19 - (1/36377123328000)*n^18 + (67/29640619008000)*n^17 - (23/219469824000)*n^16 + (19/4245696000)*n^15 - (1120937/7846046208000)*n^14 + (30866519/7846046208000)*n^13 - (315413129/3621252096000)*n^12 + (325169513/201180672000)*n^11 - (668686973/27433728000)*n^10 + (17219161039/57480192000)*n^9 - (639427718879/219469824000)*n^8 + (85152990271801/3923023104000)*n^7 - (121633558587211/1069915392000)*n^6 + (4714045506851/14859936000)*n^5 + (29982367841021/50295168000)*n^4 - (119301334227941/11027016000)*n^3 + (805259895738317/15437822400)*n^2 - (4914764430377/38798760)*n + 130960 for n>9

Example

Some solutions for n=4
..0..0..1..0....0..0..0..0....0..0..0..1....0..0..0..0....0..0..1..0
..0..1..0..1....0..0..1..1....0..0..1..0....0..0..1..1....0..1..0..0
..0..0..1..0....0..1..0..0....0..0..1..1....1..0..0..1....0..1..0..0
..1..0..0..0....1..0..1..1....1..0..0..0....0..0..0..0....1..0..0..0

Crossrefs

Sequence in context: A144465 A024050 A236421 * A291026 A239399 A193808

Adjacent sequences: A227636 A227637 A227638 * A227640 A227641 A227642

Keyword

nonn

Author

R. H. Hardin Jul 18 2013

Status

approved