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A139703
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Nonsquarefree positive integers k such that the largest prime power dividing k is prime.
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1
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20, 28, 44, 52, 60, 68, 76, 84, 88, 92, 99, 104, 116, 117, 124, 132, 136, 140, 148, 152, 153, 156, 164, 171, 172, 184, 188, 198, 204, 207, 212, 220, 228, 232, 234, 236, 244, 248, 260, 261, 264, 268, 272, 276, 279, 284, 292, 296, 304, 306, 308, 312, 316, 328
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OFFSET
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1,1
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LINKS
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FORMULA
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This sequence consists of the nonsquarefree terms of A122144.
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EXAMPLE
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99 = 3^2 * 11^1. 99 is therefore not squarefree, because it is divisible by 3^2. Also, the largest prime power dividing 99 is 11^1. This is a prime, so 99 is included in the sequence.
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MAPLE
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filter:= proc(n) local F, t, k;
F:= ifactors(n)[2];
if max(seq(t[2], t=F)) = 1 then return false fi;
k:= max[index]([seq(t[1]^t[2], t=F)]);
F[k, 2]=1
end proc:
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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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