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A112275
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Smallest number greater than n having at least as many divisors as n.
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4
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2, 3, 4, 6, 6, 8, 8, 10, 10, 12, 12, 18, 14, 15, 16, 18, 18, 20, 20, 24, 22, 24, 24, 30, 26, 27, 28, 30, 30, 36, 32, 36, 34, 35, 36, 48, 38, 39, 40, 42, 42, 48, 44, 45, 48, 48, 48, 60, 50, 52, 52, 54, 54, 56, 56, 60, 58, 60, 60, 72, 62, 63, 64, 66, 66, 70, 68, 70, 70, 72, 72, 84
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OFFSET
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1,1
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COMMENTS
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LINKS
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MAPLE
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N:= 1000: # for all terms before the first term > N
taus:= map(numtheory:-tau, [$1..N]):
for n from 1 to N do
found:= false:
for k from n+1 to N while not found do
if taus[k]>=taus[n] then found:= true; A[n]:= k fi
od;
if not found then break fi
od:
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MATHEMATICA
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kmax[n_] := 2 n;
a[n_] := Module[{tau = DivisorSigma[0, n], k},
For[k = n + 1, k <= kmax[n], k++,
If[DivisorSigma[0, k] >= tau, Return[k]]];
Print["a(n) = k not found for n = ", n]];
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CROSSREFS
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Cf. A138171 (odd n for which a(n) > n+1).
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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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