A308710 - OEIS

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A308710

Primitive practical numbers of the form 2^i * prime(k).

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

1,1

COMMENTS

Intersection of A267124 and A100368.

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.

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = 2^floor(log_2(prime(n+1))) * prime(n+1).

MATHEMATICA