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.

A067801 Numbers m such that bigomega(m)=2*omega(m).

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%I A067801 #43 Apr 24 2022 07:40:19
%S A067801 1,4,9,24,25,36,40,49,54,56,88,100,104,121,135,136,152,169,184,189,
%T A067801 196,225,232,240,248,250,289,296,297,328,336,344,351,360,361,375,376,
%U A067801 424,441,459,472,484,488,504,513,528,529,536,540,560,568,584,600,621,624
%N A067801 Numbers m such that bigomega(m)=2*omega(m).
%C A067801 There are A000041(k) distinct prime signatures of length k. - _David A. Corneth_, Apr 25 2020
%C A067801 A square k is a term iff k belongs to A062503; in this case, k = p_1^2 * p_2^2 *...* p_r^2 and bigomega(k) = 2*omega(k) = 2*r. - _Bernard Schott_, Apr 25 2020
%H A067801 Enrique Pérez Herrero, <a href="/A067801/b067801.txt">Table of n, a(n) for n = 1..5000</a>
%F A067801 Numbers m such that A001222(m) = 2*A001221(m)
%t A067801 Select[Range[700], PrimeOmega[#] == 2*PrimeNu[#] &] (* _Jean-François Alcover_, Jun 29 2013 *)
%o A067801 (PARI) is(n)=my(f=factor(n)[,2]); vecsum(f)==2*#f \\ _Charles R Greathouse IV_, Oct 15 2015
%Y A067801 Cf. A000041, A001221, A001222.
%Y A067801 Cf. also A065127 (subsequence of nonsquares), A062503 (subsequence of squares).
%K A067801 nonn
%O A067801 1,2
%A A067801 _Benoit Cloitre_, Feb 07 2002