login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A227056 Number of n X 2 -2..2 arrays of 2 X 2 subblock diagonal sums minus antidiagonal sums for some (n+1) X 3 binary array with rows and columns of the latter in lexicographically nondecreasing order. 1
10, 40, 124, 329, 777, 1673, 3341, 6269, 11164, 19018, 31186, 49477, 76259, 114579, 168299, 242249, 342398, 476044, 652024, 880945, 1175437, 1550429, 2023449, 2614949, 3348656, 4251950, 5356270, 6697549, 8316679, 10260007, 12579863 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..54

FORMULA

Empirical: a(n) = (1/5040)*n^7 + (1/180)*n^6 + (23/360)*n^5 + (25/72)*n^4 + (907/720)*n^3 + (1133/360)*n^2 + (877/210)*n + 1.

Conjectures from Colin Barker, Sep 07 2018: (Start)

G.f.: x*(10 - 40*x + 84*x^2 - 103*x^3 + 77*x^4 - 35*x^5 + 9*x^6 - x^7) / (1 - x)^8.

a(n) = 8*a(n-1) - 28*a(n-2) + 56*a(n-3) - 70*a(n-4) + 56*a(n-5) - 28*a(n-6) + 8*a(n-7) - a(n-8) for n>8.

(End)

EXAMPLE

Some solutions for n=3:

..0..0....1.-2....0..0...-2..1....0..0....1.-1....1.-1....0..0....0..1....0..1

..1..0...-1..1....0..0....0..0....1..0....0..0....0..0....0.-1....1.-2....1.-1

.-2..1....0..0....0..0....1.-1...-1..0...-2..1...-1..0....0..0...-1..1...-2..0

CROSSREFS

Column 2 of A227060.

Sequence in context: A251121 A002419 A199826 * A027981 A013977 A075060

Adjacent sequences:  A227053 A227054 A227055 * A227057 A227058 A227059

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 30 2013

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 January 29 08:12 EST 2020. Contains 331337 sequences. (Running on oeis4.)