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

 

Logo

Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 56th year, we are closing in on 350,000 sequences, and we’ve crossed 9,700 citations (which often say “discovered thanks to the OEIS”).

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A224661 Number of n X n 0..4 matrices with each 2X2 subblock idempotent 0
5, 20, 98, 180, 412, 806, 1606, 3070, 5808, 10798, 19866, 36184 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Column 4 of A224665

LINKS

Table of n, a(n) for n=1..12.

FORMULA

Empirical: a(n) = 6*a(n-1) -12*a(n-2) +5*a(n-3) +12*a(n-4) -12*a(n-5) -3*a(n-6) +6*a(n-7) -a(n-9) for n>10

EXAMPLE

Some solutions for n=3

..1..0..2....1..0..3....0..0..0....0..0..0....1..0..0....1..1..0....0..0..0

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

..4..0..1....2..0..1....2..1..1....0..0..0....0..0..1....0..0..1....4..1..1

CROSSREFS

Sequence in context: A196532 A002745 A182959 * A020046 A319731 A272218

Adjacent sequences:  A224658 A224659 A224660 * A224662 A224663 A224664

KEYWORD

nonn

AUTHOR

R. H. Hardin Apr 14 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 December 1 05:33 EST 2021. Contains 349426 sequences. (Running on oeis4.)