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A290905 a(n) = (1/2)*A290904(n). 2
0, 1, 4, 12, 36, 111, 344, 1064, 3288, 10161, 31404, 97060, 299980, 927135, 2865456, 8856144, 27371312, 84595361, 261455316, 808068924, 2497464564, 7718808463, 23856195976, 73731339384, 227878342920, 704293989585, 2176731748220, 6727533066836, 20792502889884 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

LINKS

Clark Kimberling, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (4, -4, 4, -1)

FORMULA

G.f.: x/(1 - 4 x + 4 x^2 - 4 x^3 + x^4).

a(n) = 4*a(n-1) - 4*a(n-2) + 4*a(n-3) - a(n-4).

a(n) = (1/2)*A290904(n) for n >= 0.

MATHEMATICA

z = 60; s = x/(1 - x)^2; p = 1 - 2 s^2;

Drop[CoefficientList[Series[s, {x, 0, z}], x], 1] (* A000027 *)

u = Drop[CoefficientList[Series[1/p, {x, 0, z}], x], 1] (* A290904 *)

u/2 (* A290905 *)

CROSSREFS

Cf. A000027, A290890, A290904.

Sequence in context: A170685 A177881 A290899 * A000781 A192205 A055395

Adjacent sequences:  A290902 A290903 A290904 * A290906 A290907 A290908

KEYWORD

nonn,easy

AUTHOR

Clark Kimberling, Aug 17 2017

STATUS

approved

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Last modified April 9 17:48 EDT 2020. Contains 333361 sequences. (Running on oeis4.)