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 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 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

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Last modified December 1 05:33 EST 2021. Contains 349426 sequences. (Running on oeis4.)