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.

A200511 Numbers n with omega(n)=2 and bigomega(n)>2, where omega=A001221=number of distinct prime factors, bigomega=A001222=prime factors counted with multiplicity.

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%I A200511 #18 Apr 23 2017 01:02:23
%S A200511 12,18,20,24,28,36,40,44,45,48,50,52,54,56,63,68,72,75,76,80,88,92,96,
%T A200511 98,99,100,104,108,112,116,117,124,135,136,144,147,148,152,153,160,
%U A200511 162,164,171,172,175,176,184,188,189,192,196,200,207,208,212,216,224,225,232,236
%N A200511 Numbers n with omega(n)=2 and bigomega(n)>2, where omega=A001221=number of distinct prime factors, bigomega=A001222=prime factors counted with multiplicity.
%C A200511 Equivalently, numbers of the form n=p^k*q^m where k,m>0, k+m>2 and p,q prime.
%C A200511 It appears that this is equal to A123711.
%H A200511 G. C. Greubel, <a href="/A200511/b200511.txt">Table of n, a(n) for n = 1..1000</a>
%t A200511 Select[Range[240], PrimeNu[#] == 2 && PrimeOmega[#] > 2 &] (* _Jean-François Alcover_, Jun 29 2013 *)
%o A200511 (PARI) for(n=1,999,bigomega(n)>2 & omega(n)==2 & print1(n","))
%Y A200511 Cf. A200521, A178212.
%K A200511 nonn
%O A200511 1,1
%A A200511 _M. F. Hasler_, Feb 09 2012