login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A204648 Number of (n+1) X 6 0..1 arrays with column and row pair sums b(i,j)=a(i,j)+a(i,j-1) and c(i,j)=a(i,j)+a(i-1,j) nondecreasing in column and row directions, respectively. 1
80, 137, 284, 571, 1076, 1918, 3261, 5329, 8408, 12867, 19162, 27859, 39640, 55328, 75895, 102489, 136444, 179309, 232860, 299131, 380428, 479362, 598865, 742225, 913104, 1115575, 1354142, 1633779, 1959952, 2338660, 2776459, 3280505, 3858580 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 5 of A204651.

LINKS

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

FORMULA

Empirical: a(n) = 6*a(n-1) -14*a(n-2) +14*a(n-3) -14*a(n-5) +14*a(n-6) -6*a(n-7) +a(n-8) for n>11.

Conjectures from Colin Barker, Jun 08 2018: (Start)

G.f.: x*(80 - 343*x + 582*x^2 - 335*x^3 - 292*x^4 + 600*x^5 - 379*x^6 + 89*x^7 - 4*x^8 + 8*x^9 - 4*x^10) / ((1 - x)^7*(1 + x)).

a(n) = (-10080 + 43776*n + 15308*n^2 + 2970*n^3 + 620*n^4 + 54*n^5 + 2*n^6)/1440 for n>3 and even.

a(n) = (-10890 + 43776*n + 15308*n^2 + 2970*n^3 + 620*n^4 + 54*n^5 + 2*n^6)/1440 for n>3 and odd.

(End)

EXAMPLE

Some solutions for n=5:

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

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

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

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

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

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

CROSSREFS

Cf. A204651.

Sequence in context: A261549 A068140 A224547 * A202447 A202440 A248432

Adjacent sequences:  A204645 A204646 A204647 * A204649 A204650 A204651

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 17 2012

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified November 13 12:45 EST 2019. Contains 329094 sequences. (Running on oeis4.)