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 A238777 a(n) = floor((5^n+1)/(2*3^n)). 3
 1, 1, 2, 3, 6, 10, 17, 29, 49, 82, 137, 229, 382, 638, 1063, 1772, 2953, 4923, 8205, 13675, 22792, 37987, 63312, 105521, 175868, 293114, 488524, 814207, 1357012, 2261686, 3769478, 6282463, 10470772, 17451288, 29085480 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS a(n) is the rounded-down perimeter of the Vicsek fractal after n iterations. The Vicsek fractal is a subset of the box fractal; for both types, the number of boxes = A000351(n). See illustrations in links. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Kival Ngaokrajang, Illustrations of initial terms Eric Weisstein's World of Mathematics, Box Fractal Wikipedia, Vicsek Fractal FORMULA a(n) = A034478(n)/3^n. MAPLE A238777:=n->floor((5^n+1)/(2*3^n)); seq(A238777(n), n=1..50); # Wesley Ivan Hurt, Mar 09 2014 MATHEMATICA Table[Floor[(5^n + 1)/(2*3^n)], {n, 50}] (* Wesley Ivan Hurt, Mar 09 2014 *) PROG (Small Basic) For n = 1 to 40    x = (math.Power(5, n)+1)/(2*math.Power(3, n))    a = math.Floor(x)    TextWindow.Write(a+", ") Endfor (PARI) vector(100, n, floor((5^n+1)/(2*3^n))) \\ Colin Barker, Mar 05 2014 (MAGMA) [Floor((5^n+1)/(2*3^n)): n in [1..40]]; // Vincenzo Librandi, Mar 11 2014 CROSSREFS Cf. A000351, A034478. Sequence in context: A023614 A001610 A324015 * A344615 A245437 A285665 Adjacent sequences:  A238774 A238775 A238776 * A238778 A238779 A238780 KEYWORD nonn AUTHOR Kival Ngaokrajang, Mar 05 2014 STATUS approved

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Last modified July 1 16:27 EDT 2022. Contains 354973 sequences. (Running on oeis4.)