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.

A224703 Numbers divisible by the twice the number of their prime factors (counted with multiplicity), or numbers n divisible by 2*Omega(n).

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%I A224703 #11 Apr 23 2013 11:14:29
%S A224703 2,4,12,16,18,24,30,40,42,56,66,78,80,88,96,102,104,114,120,136,138,
%T A224703 144,152,174,180,184,186,200,216,222,232,240,246,248,256,258,270,280,
%U A224703 282,296,300,318,324,328,336,344,354,360,366,376,384,402,420,424,426
%N A224703 Numbers divisible by the twice the number of their prime factors (counted with multiplicity), or numbers n divisible by 2*Omega(n).
%C A224703 A number is in the list if mod(n,2*A001222(n)) == 0.
%H A224703 Christian N. K. Anderson, <a href="/A224703/b224703.txt">Table of n, a(n) for n = 1..10000</a>
%e A224703 18 has 3 prime factors {2,3,3} and is divisible by 6=2*3; 184 has 4 prime factors {2,2,2,23} and is divisible by 8=2*4.
%t A224703 Select[Range[2, 426], Mod[#, 2*PrimeOmega[#]] == 0 &] (* _T. D. Noe_, Apr 17 2013 *)
%o A224703 (R) y=c(); i=2; isint<-function(x) x==as.integer(x)
%o A224703 while(length(y)<10000) {if(isint(i/(2*length(factorize(i))))) y=c(y,i); i=i+1 }
%Y A224703 Cf. A001222, A074946, A137230.
%K A224703 nonn
%O A224703 1,1
%A A224703 _Kevin L. Schwartz_ and _Christian N. K. Anderson_, Apr 16 2013