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A370494
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Oblong numbers of the form (k-1)*k where k is the product of an odd number of distinct primes.
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2
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2, 6, 20, 42, 110, 156, 272, 342, 506, 812, 870, 930, 1332, 1640, 1722, 1806, 2162, 2756, 3422, 3660, 4290, 4422, 4830, 4970, 5256, 6006, 6162, 6806, 7832, 9312, 10100, 10302, 10506, 10920, 11342, 11772, 11990, 12656, 12882, 16002, 16770, 17030, 18632, 18906, 19182
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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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MATHEMATICA
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Table[n*(n - 1), {n, Select[Range[150], MoebiusMu[#] == -1 &]}]
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PROG
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(PARI) lista(kmax) = forsquarefree(k=1, kmax, if(moebius(k) == -1, print1(k[1]*(k[1]-1), ", ")));
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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