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 A119251 Positive integers each with exactly 1 unitary prime divisor (i.e., n is included if and only if A056169(n) = 1). 1

%I #18 Aug 15 2023 17:02:51

%S 2,3,5,7,11,12,13,17,18,19,20,23,24,28,29,31,37,40,41,43,44,45,47,48,

%T 50,52,53,54,56,59,61,63,67,68,71,73,75,76,79,80,83,88,89,92,96,97,98,

%U 99,101,103,104,107,109,112,113,116,117,124,127,131,135,136,137,139,147

%N Positive integers each with exactly 1 unitary prime divisor (i.e., n is included if and only if A056169(n) = 1).

%C Also, numbers expressible as the product of a prime and a powerful number not divisible by that prime. - _Franklin T. Adams-Watters_, Jul 25 2006

%H Amiram Eldar, <a href="/A119251/b119251.txt">Table of n, a(n) for n = 1..10000</a>

%e 28 has the prime factorization of 2^2 * 7^1. 28 is therefore included in this sequence because there is exactly one prime raised to an exponent of 1 in 28's prime factorization.

%t Select[Range@147, Count[FactorInteger@#, 1, 2] == 1 &] (* _Robert G. Wilson v_, Jul 25 2006 *)

%Y Cf. A001694, A056169.

%K nonn

%O 1,1

%A _Leroy Quet_, Jul 23 2006

%E More terms from _Robert G. Wilson v_ and _Franklin T. Adams-Watters_, Jul 25 2006

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Last modified September 19 04:22 EDT 2024. Contains 376004 sequences. (Running on oeis4.)