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!)
A251421 Number of length n+2 0..1 arrays with the sum of the maximum minus twice the median plus the minimum of adjacent triples multiplied by some arrangement of +-1 equal to zero. 2
2, 12, 12, 40, 56, 144, 240, 544, 992, 2112, 4032, 8320, 16256, 33024, 65280, 131584, 261632, 525312, 1047552, 2099200, 4192256, 8392704, 16773120, 33562624, 67100672, 134234112, 268419072, 536903680, 1073709056, 2147549184, 4294901760 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 1 of A251428.

LINKS

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

FORMULA

Empirical: a(n) = 2*a(n-1) +2*a(n-2) -4*a(n-3).

Conjectures from Colin Barker, Mar 20 2018: (Start)

G.f.: 2*x*(1 + 4*x - 8*x^2) / ((1 - 2*x)*(1 - 2*x^2)).

a(n) = 2*(2^(n/2) + 2^n) for n even.

a(n) = 2*(2^n - 2^((n-3)/2+1)) for n odd.

(End)

EXAMPLE

Some solutions for n=10:

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

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

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

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

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

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

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

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

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

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

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

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

CROSSREFS

Cf. A251428.

Sequence in context: A088240 A168457 A045895 * A226393 A198532 A198477

Adjacent sequences:  A251418 A251419 A251420 * A251422 A251423 A251424

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 02 2014

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 April 19 22:40 EDT 2021. Contains 343117 sequences. (Running on oeis4.)