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A228151
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Denominators of r(n) = r(n-1) + r(n-2) + B_(n-2), where B_n is the n-th Bernoulli number A027641(n)/A027642(n).
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0
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1, 1, 1, 2, 3, 6, 5, 30, 105, 70, 35, 70, 231, 2310, 143, 30030, 15015, 10010, 85085, 170170, 373065, 25194, 323323, 1939938, 22309287, 14872858, 168245, 74364290, 15935205, 223092870, 1078282205, 588153930, 20056049013, 5142576670, 393255863, 9550499530
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OFFSET
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0,4
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COMMENTS
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r(n): 0, 0, 1, 1/2, 5/3, 13/6, 19/5, 179/30, 1028/105, 1103/70, 893/35,... = A227500(n)/a(n). a(0)=a(1)=1 is a choice.
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LINKS
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PROG
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(PARI) r(n) = if (n<=1, 0, r(n-1) + r(n-2) + bernfrac(n-2));
a(n) = if (n<=1, 1, denominator(r(n))); \\ Michel Marcus, Aug 24 2013
(Magma) t:=40; r:=[n le 2 select 0 else Self(n-1)+Self(n-2)+BernoulliNumber(n-3): n in [1..t]]; [n le 2 select 1 else Denominator(r[n]): n in [1..t]]; // Bruno Berselli, Sep 05 2013
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CROSSREFS
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Cf. A227500: numerators of r(n), where a(n) is named c(n).
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KEYWORD
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nonn,frac
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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