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 A206450 Number of 0..3 arrays of length n avoiding the consecutive pattern 0..3. 4
 4, 16, 64, 255, 1016, 4048, 16128, 64257, 256012, 1020000, 4063872, 16191231, 64508912, 257015648, 1023998720, 4079803649, 16254705684, 64761807088, 258023229632, 1028013114879, 4095797753832, 16318429208240, 65015693603328 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Column 3 of A206455. LINKS R. H. Hardin, Table of n, a(n) for n = 1..210 Index entries for linear recurrences with constant coefficients, signature (4,0,0,-1). FORMULA a(n) = 4*a(n-1) -a(n-4). Empirical: a(n) = sum{i in 0..floor(n/4)} ((-1)^i*4^(n-4*i)*binomial(n-3*i,i)). g.f.: x*(4 - x^3) / (1 - 4*x + x^4). - Colin Barker, Feb 23 2018 CROSSREFS Cf. A206455. Sequence in context: A269651 A077821 A215877 * A294452 A270142 A000302 Adjacent sequences:  A206447 A206448 A206449 * A206451 A206452 A206453 KEYWORD nonn,easy AUTHOR R. H. Hardin, Feb 07 2012 STATUS approved

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Last modified September 24 03:26 EDT 2021. Contains 347623 sequences. (Running on oeis4.)