A224598 Number of (n+2)X(n+2) 0..2 matrices with each 3X3 subblock idempotent

122, 272, 482, 666, 1202, 2092, 3308, 5398, 8876, 14232, 22734, 36346, 57712, 91204, 143828, 226126, 354436, 554296, 865004, 1347042, 2093774, 3248860, 5032926, 7784734, 12023856, 18546144

Offset

1,1

Comments

Diagonal of A224606

Links

Table of n, a(n) for n=1..26.

Christian Ballot, Clark Kimberling, and Peter J. C. Moses, Linear Recurrences Originating From Polynomial Trees, Fibonacci Quart. 55 (2017), no. 5, 15-27. Mentions this sequence.

Formula

Empirical: a(n) = 6*a(n-1) -15*a(n-2) +23*a(n-3) -30*a(n-4) +36*a(n-5) -34*a(n-6) +27*a(n-7) -21*a(n-8) +13*a(n-9) -6*a(n-10) +3*a(n-11) -a(n-12) for n>14

Example

Some solutions for n=3
..1..0..0..0..0....0..1..0..0..2....1..1..1..0..2....1..1..1..0..1
..1..0..0..0..0....0..1..0..0..1....0..0..0..0..0....0..0..0..0..0
..1..0..0..0..0....0..1..0..0..1....0..0..0..0..0....0..0..0..0..0
..2..0..0..0..0....0..1..0..0..1....0..0..0..0..0....2..1..1..1..1
..1..0..0..0..0....0..2..0..0..1....0..2..1..1..1....0..0..0..0..0

Crossrefs

Sequence in context: A004925 A369598 A276303 * A070955 A195856 A116216

Adjacent sequences: A224595 A224596 A224597 * A224599 A224600 A224601

Keyword

nonn

Author

R. H. Hardin, Apr 11 2013

Status

approved