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 A262719 a(n) is the smallest nonnegative k such that there is no 3 X 3 matrix with entries in {1,...,n} whose determinant is k. 1
 1, 6, 21, 55, 110, 203, 357, 544, 808, 1177, 1670, 2215, 2865, 3599, 4558, 5621, 6637, 8041, 9769, 11413, 13394, 15593, 17683, 20317, 23249, 26063, 29506, 33287, 37461, 41692, 46306, 50707, 55667, 61723, 67547, 73939, 80767, 87941, 94913, 101613, 111422 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Hiroaki Yamanouchi, Table of n, a(n) for n = 1..50 EXAMPLE For n=1, the only matrix is the matrix of all 1s, which has determinant 0. Hence, a(1)=1. PROG (Python) from itertools import product, groupby, count . def det(m): ...a, b, c, d, e, f, g, h, i = m ...return abs(a*(e*i-f*h)-b*(d*i-f*g)+c*(d*h-e*g)) . def a262719(n): ...s = list(product(range(1, n+1), repeat=9)) ...i = 0 ...for k, ms in groupby(sorted(s, key=det), key=det): ......if k!=i: .........return i ......i += 1 ...return i CROSSREFS Sequence in context: A067680 A115052 A025203 * A238702 A162539 A259474 Adjacent sequences:  A262716 A262717 A262718 * A262720 A262721 A262722 KEYWORD nonn AUTHOR Christian Perfect, Sep 28 2015 EXTENSIONS a(7)-a(41) from Hiroaki Yamanouchi, Oct 17 2015 STATUS approved

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Last modified January 27 08:31 EST 2020. Contains 331293 sequences. (Running on oeis4.)