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 A037604 Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,2,3. 1
 1, 6, 27, 109, 438, 1755, 7021, 28086, 112347, 449389, 1797558, 7190235, 28760941, 115043766, 460175067, 1840700269, 7362801078, 29451204315, 117804817261, 471219269046, 1884877076187, 7539508304749, 30158033218998 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Convolution of A000302 with A010882. - Philippe Deléham, Mar 24 2013 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..1661 Index entries for linear recurrences with constant coefficients, signature (4,0,1,-4). FORMULA G.f.: x*(1+2x+3*x^2)/((1-x)*(1-4x)*(1+x+x^2)). - Philippe Deléham, Mar 24 2013 a(n) = 4*a(n-1) + a(n-3) -4*a(n-4) for n > 5, a(1) = 1, a(2) = 6, a(3) = 27, a(4) = 109, a(5) = 438. - Philippe Deléham, Mar 24 2013 a(n+2) = 6*A033140(n) + A191597(n+2). - Philippe Deléham, Mar 24 2013 A007090(a(n)) = A037610(n). - R. J. Mathar, Apr 27 2015 a(n) = floor(3*4^n/7). - Karl V. Keller, Jr., Mar 18 2021 MATHEMATICA Rest@ CoefficientList[Series[x (1 + 2 x + 3 x^2)/((1 - x) (1 - 4 x) (1 + x + x^2)), {x, 0, 23}], x] (* Michael De Vlieger, Mar 19 2021 *) PROG (PARI) a(n)=([0, 1, 0, 0; 0, 0, 1, 0; 0, 0, 0, 1; -4, 1, 0, 4]^(n-1)*[1; 6; 27; 109])[1, 1] \\ Charles R Greathouse IV, Feb 13 2017 (Python) print([3*4**n//7 for n in range(1, 24)]) # Karl V. Keller, Jr., Mar 18 2021 CROSSREFS Cf. A000302, A010882. Sequence in context: A318638 A094829 A055145 * A022634 A094788 A221863 Adjacent sequences:  A037601 A037602 A037603 * A037605 A037606 A037607 KEYWORD nonn,base,easy AUTHOR STATUS approved

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Last modified July 29 06:21 EDT 2021. Contains 346340 sequences. (Running on oeis4.)