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A309403
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Total sum of the number of divisors of the element sum over all nonempty subsets of [n].
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3
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1, 5, 16, 40, 96, 217, 469, 1011, 2147, 4497, 9389, 19489, 40256, 82948, 170413, 349158, 714153, 1458199, 2972683, 6052561, 12308971, 25006177, 50755272, 102933086, 208594116, 422432018, 854956112, 1729360940, 3496259940, 7065053883, 14270420877, 28812580857
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OFFSET
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1,2
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LINKS
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MAPLE
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b:= proc(n, s) option remember; `if`(n=0,
numtheory[tau](s), b(n-1, s)+b(n-1, s+n))
end:
a:= n-> b(n, 0):
seq(a(n), n=1..30);
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MATHEMATICA
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b[n_, s_] := b[n, s] = If[n == 0,
If[s == 0, 0, DivisorSigma[0, s]], b[n-1, s] + b[n-1, s+n]];
a[n_] := b[n, 0];
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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