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 A145676 Number of n X n {0,-1,1}-matrices A such that permanent( |A| ) = det A, where |A| is obtained from A by taking the absolute value of each entry. 2
 1, 2, 49, 8419, 9162049 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS EXAMPLE Here are the 2 for the 1 X 1 case: {{{0}}, {{1}}} and the 49 for the 2 X 2 case: {{{-1, -1}, {0, -1}}, {{-1, -1}, {0, 0}}, {{-1, -1}, {1, -1}}, {{-1, -1}, {1, 0}}, {{-1, 0}, {-1, -1}}, {{-1, 0}, {-1, 0}}, {{-1, 0}, {0, -1}}, {{-1, 0}, {0, 0}}, {{-1, 0}, {1, -1}}, {{-1, 0}, {1, 0}}, {{-1, 1}, {-1, -1}}, {{-1, 1}, {-1, 0}}, {{-1, 1}, {0, -1}}, {{-1, 1}, {0, 0}}, {{0, -1}, {0, -1}}, {{0, -1}, {0, 0}}, {{0, -1}, {0, 1}}, {{0, -1}, {1, -1}}, {{0, -1}, {1, 0}}, {{0, -1}, {1, 1}}, {{0, 0}, {-1, -1}}, {{0, 0}, {-1, 0}}, {{0, 0}, {-1, 1}}, {{0, 0}, {0, -1}}, {{0, 0}, {0, 0}}, {{0, 0}, {0, 1}}, {{0, 0}, {1, -1}}, {{0, 0}, {1, 0}}, {{0, 0}, {1, 1}}, {{0, 1}, {-1, -1}}, {{0, 1}, {-1, 0}}, {{0, 1}, {-1, 1}}, {{0, 1}, {0, -1}}, {{0, 1}, {0, 0}}, {{0, 1}, {0, 1}}, {{1, -1}, {0, 0}}, {{1, -1}, {0, 1}}, {{1, -1}, {1, 0}}, {{1, -1}, {1, 1}}, {{1, 0}, {-1, 0}}, {{1, 0}, {-1, 1}}, {{1, 0}, {0, 0}}, {{1, 0}, {0, 1}}, {{1, 0}, {1, 0}}, {{1, 0}, {1, 1}}, {{1, 1}, {-1, 0}}, {{1, 1}, {-1, 1}}, {{1, 1}, {0, 0}}, {{1, 1}, {0, 1}}} CROSSREFS Cf. A145675. Sequence in context: A257742 A269839 A088067 * A335406 A291188 A225795 Adjacent sequences:  A145673 A145674 A145675 * A145677 A145678 A145679 KEYWORD nonn AUTHOR Eric W. Weisstein, Mar 26 2009 EXTENSIONS a(4) from Eric W. Weisstein, Mar 27 2009 STATUS approved

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Last modified September 23 13:56 EDT 2021. Contains 347617 sequences. (Running on oeis4.)