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A079431
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Least m>n with same smallest odd prime factor as n.
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2
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2, 4, 6, 8, 10, 9, 14, 16, 12, 20, 22, 15, 26, 28, 18, 32, 34, 21, 38, 25, 24, 44, 46, 27, 35, 52, 30, 49, 58, 33, 62, 64, 36, 68, 40, 39, 74, 76, 42, 50, 82, 45, 86, 88, 48, 92, 94, 51, 56, 55, 54, 104, 106, 57, 65, 77, 60, 116, 118, 63, 122, 124, 66, 128, 70, 69, 134, 136
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OFFSET
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1,1
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COMMENTS
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a(2^k) = 2^(k+1), as A078701(2^k) = 1.
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LINKS
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MAPLE
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N:= 100:
A:= Vector(N):
p:= 2:
do
p:= nextprime(p);
if p > N then break fi;
R:= select(k -> A[k] = 0, [$1..N]);
S:= select(`<=`, R, N/p);
A[p*S]:= Vector(p*R[2..1+nops(S)]);
od:
for k from 0 to ilog2(N) do A[2^k]:= 2^(k+1) od:
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MATHEMATICA
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sopf[n_] := SelectFirst[FactorInteger[n][[All, 1]], # > 2&];
a[n_] := For[p = sopf[n]; m = n+1, True, m++, If[p == sopf[m], Return[m]]];
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CROSSREFS
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KEYWORD
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AUTHOR
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STATUS
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approved
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