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A322927
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Expansion of x*(1 + 5*x + 40*x^2)/((1 - x^2)*(1 - 10*x^2)).
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1
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0, 1, 5, 51, 55, 551, 555, 5551, 5555, 55551, 55555, 555551, 555555, 5555551, 5555555, 55555551, 55555555, 555555551, 555555555, 5555555551, 5555555555, 55555555551, 55555555555, 555555555551, 555555555555, 5555555555551, 5555555555555, 55555555555551
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OFFSET
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0,3
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LINKS
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Muniru A Asiru, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0,11,0,-10).
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FORMULA
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G.f.: x*(1 + 5*x + 40*x^2)/((1 - x^2)*(1 - 10*x^2)).
a(n) = 11*a(n-2) - 10*a(n-4).
a(n) = 5*(10^n - 1)/9 for n even; a(n) = (5*10^n - 41)/9 otherwise.
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MAPLE
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seq(coeff(series(x*(1+5*x+40*x^2)/((1-x^2)*(1-10*x^2)), x, n+1), x, n), n = 0 .. 30); # Muniru A Asiru, Mar 17 2019
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MATHEMATICA
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CoefficientList[Series[x (1 + 5 x + 40 x^2) / (10 x^4 - 11 x^2 + 1), {x, 0, 25}], x]
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PROG
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(Magma) I:=[0, 1, 5, 51]; [n le 4 select I[n] else 11*Self(n-2)-10*Self(n-4): n in [1..30]];
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CROSSREFS
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Bisections give: A002279 (even part), A173804 (odd part).
Sequence in context: A160779 A077681 A326738 * A333261 A117710 A064019
Adjacent sequences: A322924 A322925 A322926 * A322928 A322929 A322930
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KEYWORD
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nonn,easy
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AUTHOR
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Vincenzo Librandi, Mar 17 2019
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STATUS
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approved
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