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A182716
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Number of 2's in all partitions of 2n that do not contain 1 as a part.
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1
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0, 1, 2, 4, 8, 15, 27, 48, 82, 137, 225, 362, 572, 892, 1370, 2078, 3117, 4624, 6791, 9885, 14263, 20416, 29007, 40921, 57345, 79864, 110565, 152211, 208435, 283982, 385048, 519695, 698346, 934477, 1245439, 1653485, 2187108, 2882686, 3786497, 4957324, 6469625
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OFFSET
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0,3
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LINKS
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MAPLE
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b:= proc(n, i) option remember; local r;
if n<=0 or i<2 then 0
elif i=2 then `if`(irem(n, 2, 'r')=0, r, 0)
else b(n, i-1) +b(n-i, i)
fi
end:
a:= n-> b(2*n, 2*n):
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MATHEMATICA
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b[n_, i_] := b[n, i] = Module[{q, r}, Which[n <= 0 || i<2, 0, i==2, {q, r} = QuotientRemainder[n, 2]; If[r==0, q, 0], True, b[n, i-1]+b[n-i, i]]]; a[n_] := b[2n, 2n]; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Feb 21 2017, after Alois P. Heinz *)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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