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Numbers of the form p^k * q, p and q prime, p > q, k > 0.
4

%I #11 Apr 16 2019 17:30:47

%S 6,10,14,15,18,21,22,26,33,34,35,38,39,46,50,51,54,55,57,58,62,65,69,

%T 74,75,77,82,85,86,87,91,93,94,95,98,106,111,115,118,119,122,123,129,

%U 133,134,141,142,143,145,146,147,155,158,159,161,162,166,177,178

%N Numbers of the form p^k * q, p and q prime, p > q, k > 0.

%H Robert Israel, <a href="/A325230/b325230.txt">Table of n, a(n) for n = 1..10000</a>

%e The sequence of terms together with their prime indices begins:

%e 6: {1,2}

%e 10: {1,3}

%e 14: {1,4}

%e 15: {2,3}

%e 18: {1,2,2}

%e 21: {2,4}

%e 22: {1,5}

%e 26: {1,6}

%e 33: {2,5}

%e 34: {1,7}

%e 35: {3,4}

%e 38: {1,8}

%e 39: {2,6}

%e 46: {1,9}

%e 50: {1,3,3}

%e 51: {2,7}

%e 54: {1,2,2,2}

%e 55: {3,5}

%e 57: {2,8}

%e 58: {1,10}

%p filter:= proc(n) local F;

%p F:= sort(ifactors(n)[2],(a,b)-> a[1]<b[1]);

%p nops(F) = 2 and F[1,2] = 1;

%p end proc:

%p select(filter, [$6..200]); # _Robert Israel_, Apr 14 2019

%t Select[Range[100],PrimeOmega[#/Power@@FactorInteger[#][[-1]]]==1&]

%o (Python)

%o from sympy import factorint

%o A325230_list = [n for n, m in ((n, factorint(n)) for n in range(2,10**6)) if len(m) == 2 and m[min(m)] == 1] # _Chai Wah Wu_, Apr 16 2019

%Y Positions of 1's in A325226.

%Y Cf. A056239, A093641, A112798, A174090, A257541, A307517, A325223, A325224, A325225, A325231.

%K nonn

%O 1,1

%A _Gus Wiseman_, Apr 13 2019