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 A347281 a(n) = 2^(n - 1)*permanent(M_n)^2 where M_n is the n X n matrix M_n(j, k) = cos(Pi*j*k/n). 1
 1, 2, 4, 0, 36, 288, 144, 18432, 11664, 115200, 144400, 0, 808151184, 133693952, 262440000, 299649466368, 7937314520976, 73575242956800, 21204146201616, 6459752448000000, 212406372892224, 8753824001424826368, 195844025123172289600, 152252829159294763008, 26487254903393025000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Table of n, a(n) for n=1..25. EXAMPLE a(7) = -3384288*cos(Pi/7) - 3460896*sin(Pi/14) - 45888*cos(2*Pi/7) - 28224*cos(15*Pi/7) + 48384*cos(17*Pi/7) + 1706400 + 3458400*sin(3*Pi/14) = 144. - Chai Wah Wu, Sep 19 2021 PROG (PARI) P(n)=matpermanent(matrix(n, n, j, k, cos((Pi*j*k)/n))); for(k=1, 25, print1(round(2^(k-1)*P(k)^2), ", ")) CROSSREFS Cf. A085524, A085530, A000169, A085527, A347929. Sequence in context: A009170 A009625 A308024 * A055871 A012716 A173220 Adjacent sequences: A347278 A347279 A347280 * A347282 A347283 A347284 KEYWORD nonn AUTHOR Hugo Pfoertner, Sep 18 2021 STATUS approved

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Last modified July 13 20:42 EDT 2024. Contains 374288 sequences. (Running on oeis4.)