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 A197989 Number of binary arrangements of total n 1's, without adjacent 1's on n X n array connected n-s 4
 1, 4, 45, 886, 24395, 860336, 36914493, 1863645610, 108131503623, 7085585223652, 517329551346608, 41634263983867842, 3661077644199252550, 349191617521920855488, 35902782820742394839453, 3958207187579046500083794, 465777357329812920074875295 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Vaclav Kotesovec, Table of n, a(n) for n = 1..108 V. Kotesovec, Non-attacking chess pieces, 6ed, p.373-381 FORMULA Asymptotic (V. Kotesovec, Oct 15 2011): a(n) ~ n^(2n)/n!*exp(-3/2). MATHEMATICA permopak[part_, k_]:=(hist=ConstantArray[0, k]; Do[hist[[part[[t]]]]++, {t, 1, Length[part]}]; (Length[part])!/Product[(hist[[t]])!, {t, 1, k}]); waz1n[k_, n_]:=(If[n-k+1

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Last modified May 28 16:29 EDT 2024. Contains 372916 sequences. (Running on oeis4.)