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 A181252 Number of n X 9 binary matrices with no 2 X 2 block having four 1's. 1
 512, 169209, 61986457, 22161786304, 7969215344753, 2861765993703849, 1027999596778673856, 369248337357375835969, 132633131268024896655873, 47641303155727829675539968, 17112587585474467714330327353 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 9 of A181253. LINKS R. H. Hardin, Table of n, a(n) for n=1..200 Robert Israel, Maple-assisted derivation of recurrence Robert Israel, Linear recurrence of order 48 FORMULA Linear recurrence of order 48: see link. - Robert Israel, Apr 02 2020 MAPLE for i from 1 to 512 do Configs[i]:= convert(2^9+i-1, base, 2)[1..9] od: Compatible:= proc(i, j) if `and`(seq(evalb(Configs[i][k] + Configs[i][k+1] + Configs[j][k]+Configs[j][k+1] < 4), k=1..8)) then 1 else 0 fi end proc: T:= Matrix(512, 512, Compatible): v:= Vector(512, 1): TV[0]:= v: for nn from 1 to 23 do TV[nn]:= T . TV[nn-1] od: seq(v^%T . TV[n], n=0..23); # Robert Israel, Apr 02 2020 CROSSREFS Cf. A181253. Sequence in context: A291461 A328200 A181244 * A016749 A144323 A320861 Adjacent sequences: A181249 A181250 A181251 * A181253 A181254 A181255 KEYWORD nonn AUTHOR R. H. Hardin, Oct 10 2010 STATUS approved

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Last modified September 29 23:48 EDT 2023. Contains 365781 sequences. (Running on oeis4.)