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 A220472 T(n,k)=Number of idempotent n X n -k..k matrices of rank 2 0
 0, 0, 1, 0, 1, 75, 0, 1, 399, 4470, 0, 1, 927, 90390, 224810, 0, 1, 1815, 424374 (list; table; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS Table starts ......0.....0......0....0.0.0 ......1.....1......1....1.1 .....75...399....927.1815 ...4470.90390.424374 .224810 LINKS Table of n, a(n) for n=1..19. EXAMPLE Some solutions for n=3 k=4 ..2.-2..2....1..0..0....1..1..0....3..2.-2...-1..3.-2....1..0..0...-1..2..0 ..0..1..0...-3..1.-1....0..0..0....1..2.-1...-2..4.-2...-4..1..4...-1..2..0 .-1..2.-1...-3..0..0....0..2..1....4..4.-3...-2..3.-1....1..0..0....1.-1..1 CROSSREFS Row 3 is A223452 Sequence in context: A257534 A063680 A277841 * A033395 A143754 A357040 Adjacent sequences: A220469 A220470 A220471 * A220473 A220474 A220475 KEYWORD nonn,tabl AUTHOR R. H. Hardin Apr 10 2013 STATUS approved

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Last modified February 25 00:32 EST 2024. Contains 370308 sequences. (Running on oeis4.)