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A037597
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Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,0.
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2
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1, 7, 28, 113, 455, 1820, 7281, 29127, 116508, 466033, 1864135, 7456540, 29826161, 119304647, 477218588, 1908874353, 7635497415, 30541989660, 122167958641, 488671834567, 1954687338268, 7818749353073, 31274997412295
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OFFSET
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1,2
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LINKS
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FORMULA
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G.f.: x*(1+3*x) / ( (x-1)*(4*x-1)*(1+x+x^2) ).
a(n) = 4*a(n-1) + a(n-3) - 4*a(n-4). (End)
a(1)=1, a(2)=7, a(n) = 5*a(n-1) - 4*a(n-2) + (period 3: repeat -3, 1, 2). - Vincenzo Librandi, Jun 06 2011
E.g.f.: 2*(2*exp(x)*(exp(3*x) - 1) - sqrt(3)*exp(-x/2)*sin(sqrt(3)*x/x))/9. - Stefano Spezia, Oct 02 2023
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MAPLE
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PROG
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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STATUS
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approved
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