cp's OEIS Frontend

A360552 Numbers > 1 whose distinct prime factors have integer median.

%I A360552 #5 Feb 16 2023 13:41:53
%S A360552 2,3,4,5,7,8,9,11,13,15,16,17,19,21,23,25,27,29,30,31,32,33,35,37,39,
%T A360552 41,42,43,45,47,49,51,53,55,57,59,60,61,63,64,65,66,67,69,70,71,73,75,
%U A360552 77,78,79,81,83,84,85,87,89,90,91,93,95,97,99,101,102,103
%N A360552 Numbers > 1 whose distinct prime factors have integer median.
%C A360552 The median of a multiset is either the middle part (for odd length), or the average of the two middle parts (for even length).
%e A360552 The prime factors of 900 are {2,2,3,3,5,5}, with distinct parts {2,3,5}, with median 3, so 900 is in the sequence.
%t A360552 Select[Range[2,100],IntegerQ[Median[First/@FactorInteger[#]]]&]
%Y A360552 For mean instead of median we have A078174, complement of A176587.
%Y A360552 The complement is A100367 (without 1).
%Y A360552 Positions of even terms in A360458.
%Y A360552 - For divisors (A063655) we have A139711, complement A139710.
%Y A360552 - For prime indices (A360005) we have A359908, complement A359912.
%Y A360552 - For distinct prime indices (A360457) we have A360550, complement A360551.
%Y A360552 - For distinct prime factors (A360458) we have A360552, complement A100367.
%Y A360552 - For prime factors (A360459) we have A359913, complement A072978.
%Y A360552 - For prime multiplicities (A360460) we have A360553, complement A360554.
%Y A360552 - For 0-prepended differences (A360555) we have A360556, complement A360557.
%Y A360552 A027746 lists prime factors, length A001222, indices A112798.
%Y A360552 A027748 lists distinct prime factors, length A001221, indices A304038.
%Y A360552 A323171/A323172 = mean of distinct prime factors, indices A326619/A326620.
%Y A360552 A325347 = partitions w/ integer median, complement A307683, strict A359907.
%Y A360552 A359893 and A359901 count partitions by median, odd-length A359902.
%Y A360552 Cf. A000975, A026424, A056239, A078175, A175352, A316413, A326621, A360009.
%K A360552 nonn
%O A360552 1,1
%A A360552 _Gus Wiseman_, Feb 16 2023