cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A360558 Numbers whose multiset of prime factors (or indices, see A112798) has more adjacent equalities (or parts that have appeared before) than distinct parts.

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%I A360558 #6 Feb 21 2023 23:24:39
%S A360558 8,16,27,32,48,64,72,80,81,96,108,112,125,128,144,160,162,176,192,200,
%T A360558 208,216,224,243,256,272,288,304,320,324,343,352,368,384,392,400,405,
%U A360558 416,432,448,464,480,486,496,500,512,544,567,576,592,608,625,640,648
%N A360558 Numbers whose multiset of prime factors (or indices, see A112798) has more adjacent equalities (or parts that have appeared before) than distinct parts.
%C A360558 No terms are squarefree.
%C A360558 Also numbers whose first differences of 0-prepended prime indices have median 0.
%F A360558 A001222(a(n)) > 2*A001221(a(n)).
%e A360558 The terms together with their prime indices begin:
%e A360558      8: {1,1,1}
%e A360558     16: {1,1,1,1}
%e A360558     27: {2,2,2}
%e A360558     32: {1,1,1,1,1}
%e A360558     48: {1,1,1,1,2}
%e A360558     64: {1,1,1,1,1,1}
%e A360558     72: {1,1,1,2,2}
%e A360558     80: {1,1,1,1,3}
%e A360558     81: {2,2,2,2}
%e A360558     96: {1,1,1,1,1,2}
%e A360558    108: {1,1,2,2,2}
%e A360558    112: {1,1,1,1,4}
%e A360558    125: {3,3,3}
%e A360558 For example, the prime indices of 720 are {1,1,1,1,2,2,3} with 4 adjacent equalities and 3 distinct parts, so 720 is in the sequence.
%t A360558 Select[Range[100],PrimeOmega[#]>2*PrimeNu[#]&]
%Y A360558 For equality we have A067801.
%Y A360558 These partitions are counted by A360254.
%Y A360558 A112798 lists prime indices, length A001222, sum A056239.
%Y A360558 A326567/A326568 gives mean of prime indices.
%Y A360558 A360005 gives median of prime indices (times 2).
%Y A360558 Cf. A000975, A027193, A067340, A237363, A317090, A360248, A360249, A360454, A360555, A360556.
%K A360558 nonn
%O A360558 1,1
%A A360558 _Gus Wiseman_, Feb 20 2023