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A225011 Number of 4 X n 0..1 arrays with rows unimodal and columns nondecreasing. 2
5, 25, 95, 295, 791, 1897, 4166, 8518, 16414, 30086, 52834, 89402, 146446, 233108, 361711, 548591, 815083, 1188679, 1704377, 2406241, 3349193, 4601059, 6244892, 8381596, 11132876, 14644540, 19090180, 24675260, 31641640, 40272566, 50898157 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A225010.

Apparently also column 5 of A071920. - R. J. Mathar, May 17 2014

LINKS

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

FORMULA

Empirical: a(n) = (1/40320)*n^8 + (1/1440)*n^7 + (3/320)*n^6 + (5/72)*n^5 + (629/1920)*n^4 + (1279/1440)*n^3 + (16763/10080)*n^2 + (25/24)*n + 1 = 1 + n* (n+1) *(n^6 + 27*n^5 + 351*n^4 + 2449*n^3 + 10760*n^2 + 25052*n + 42000)/40320.

Empirical: G.f.: -x*(x^4 - 5*x^3 + 10*x^2 - 10*x + 5) *(x^4 - 3*x^3 + 4*x^2 - 2*x + 1) / (x-1)^9 . - R. J. Mathar, May 17 2014

EXAMPLE

Some solutions for n=3

..0..1..0....0..0..0....0..0..1....0..0..0....1..0..0....1..0..0....0..0..1

..0..1..1....0..1..0....0..1..1....0..0..0....1..0..0....1..0..0....0..0..1

..1..1..1....0..1..0....1..1..1....0..0..0....1..1..0....1..0..0....0..0..1

..1..1..1....0..1..0....1..1..1....0..0..1....1..1..0....1..1..1....0..1..1

CROSSREFS

Sequence in context: A147177 A057255 A134140 * A228457 A213293 A203184

Adjacent sequences:  A225008 A225009 A225010 * A225012 A225013 A225014

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 23 2013

STATUS

approved

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Last modified October 20 12:47 EDT 2019. Contains 328257 sequences. (Running on oeis4.)