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 A208948 Number of 6-bead necklaces labeled with numbers -n..n not allowing reversal, with sum zero with no three beads in a row equal. 1
 20, 264, 1464, 5238, 14430, 33468, 68722, 128844, 225126, 371858, 586668, 890880, 1309872, 1873416, 2616036, 3577366, 4802490, 6342300, 8253854, 10600716, 13453314, 16889298, 20993880, 25860192, 31589644, 38292264, 46087056, 55102358 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Row 6 of A208945. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 FORMULA Empirical: a(n) = 5*a(n-1) - 10*a(n-2) + 11*a(n-3) - 10*a(n-4) + 11*a(n-5) - 10*a(n-6) + 5*a(n-7) - a(n-8). Empirical g.f.: 2*x*(10 + 82*x + 172*x^2 + 169*x^3 + 88*x^4 + 7*x^5) / ((1 - x)^6*(1 + x + x^2)). - Colin Barker, Jul 07 2018 EXAMPLE Some solutions for n=5: -3 -4 -5 -2 -4 -2 -5 -4 -5 -5 -5 -4 -5 -3 -5 -4 -1 4 -2 -1 -1 0 -2 1 -1 5 -4 -3 0 5 2 2 -2 0 0 -2 0 2 -3 2 3 1 3 3 3 -2 3 0 2 -1 0 3 4 1 3 -2 -5 2 1 1 -3 -2 5 -4 1 3 3 3 -1 0 3 4 3 -4 1 1 4 -1 -3 4 3 -2 4 -1 2 -1 4 -1 5 1 4 2 1 3 -2 2 CROSSREFS Cf. A208945. Sequence in context: A022111 A025943 A025961 * A278408 A229562 A021854 Adjacent sequences: A208945 A208946 A208947 * A208949 A208950 A208951 KEYWORD nonn AUTHOR R. H. Hardin, Mar 03 2012 STATUS approved

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Last modified June 8 18:04 EDT 2023. Contains 363165 sequences. (Running on oeis4.)