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A308710
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Primitive practical numbers of the form 2^i * prime(k).
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5
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6, 20, 28, 88, 104, 272, 304, 368, 464, 496, 1184, 1312, 1376, 1504, 1696, 1888, 1952, 4288, 4544, 4672, 5056, 5312, 5696, 6208, 6464, 6592, 6848, 6976, 7232, 8128, 16768, 17536, 17792, 19072, 19328, 20096, 20864, 21376, 22144, 22912, 23168, 24448, 24704, 25216
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OFFSET
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1,1
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COMMENTS
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a(n) is a number of the form 2^i * prime(k) for i > 0 and A007053(i) < k <= A007053(i+1).
Terms are pseudoperfect numbers, A005835 and are also primitive pseudoperfect numbers, A006036.
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LINKS
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FORMULA
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a(n) = 2^floor(log_2(prime(n+1))) * prime(n+1).
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MATHEMATICA
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a[n_] := (p = Prime[n+1]) * 2^Floor[Log2[p]]; Array[a, 50] (* Amiram Eldar, Sep 22 2019 *)
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PROG
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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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