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A100427
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Bisection of A000081 (odd part).
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3
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1, 2, 9, 48, 286, 1842, 12486, 87811, 634847, 4688676, 35221832, 268282855, 2067174645, 16083734329, 126186554308, 997171512998, 7929819784355, 63411730258053, 509588049810620, 4113254119923150, 33333125878283632, 271097737169671824, 2212039245722726118
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OFFSET
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0,2
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LINKS
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MAPLE
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with(numtheory):
b:= proc(n) option remember; local d, j; `if`(n<2, n,
(add(add(d*b(d), d=divisors(j))*b(n-j), j=1..n-1))/(n-1))
end:
a:= n-> b(2*n+1):
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MATHEMATICA
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b[n_] := b[n] = If[n <= 1, n, Sum[Sum[d*b[d], {d, Divisors[j]}]*b[n-j], {j, 1, n-1}]/(n-1)]; a[n_] := b[2*n+1]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Mar 19 2014, after Alois P. Heinz *)
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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