

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
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OFFSET

1,1


COMMENTS

Column 4 of A224665


LINKS

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


FORMULA

Empirical: a(n) = 6*a(n1) 12*a(n2) +5*a(n3) +12*a(n4) 12*a(n5) 3*a(n6) +6*a(n7) a(n9) 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



