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A224668 Number of 6 X 6 0..n matrices with each 2 X 2 subblock idempotent. 1
428, 542, 668, 806, 956, 1118, 1292, 1478, 1676, 1886, 2108, 2342, 2588, 2846, 3116, 3398, 3692, 3998, 4316, 4646, 4988, 5342, 5708, 6086, 6476, 6878, 7292, 7718, 8156, 8606, 9068, 9542, 10028, 10526, 11036, 11558, 12092, 12638, 13196, 13766, 14348 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

FORMULA

Empirical: a(n) = 6*n^2 + 96*n + 326.

Conjectures from Colin Barker, Sep 02 2018: (Start)

G.f.: 2*x*(214 - 371*x + 163*x^2) / (1 - x)^3.

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) for n>3.

(End)

EXAMPLE

Some solutions for n=3:

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

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

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

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

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

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

CROSSREFS

Row 6 of A224665.

Sequence in context: A095811 A235217 A236383 * A030467 A253505 A173798

Adjacent sequences:  A224665 A224666 A224667 * A224669 A224670 A224671

KEYWORD

nonn

AUTHOR

R. H. Hardin, Apr 14 2013

STATUS

approved

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Last modified November 11 16:04 EST 2019. Contains 329019 sequences. (Running on oeis4.)