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.

A077617 Numbers k such that Omega(k) = Omega(k+1) + Omega(k+2).

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%I A077617 #16 Sep 08 2022 08:45:07
%S A077617 12,16,24,40,45,48,56,84,100,105,132,136,140,165,168,189,204,210,224,
%T A077617 228,261,264,272,297,315,330,345,357,372,378,380,405,441,444,450,464,
%U A077617 465,468,477,496,513,520,522,525,536,544,546,561,564,567,588,608,621
%N A077617 Numbers k such that Omega(k) = Omega(k+1) + Omega(k+2).
%C A077617 Omega(n) denotes the number of prime factors of n, counting multiplicity.
%H A077617 Amiram Eldar, <a href="/A077617/b077617.txt">Table of n, a(n) for n = 1..10000</a>
%e A077617 a(2) = 16 is a term because Omega(16) = 4 = Omega(17) + Omega(18) = 1 + 3 = 4.
%t A077617 Select[Range[1, 1000], PrimeOmega[#] == PrimeOmega[# + 1] + PrimeOmega[# + 2] &] (* _Vaclav Kotesovec_, Feb 13 2019 *)
%t A077617 Position[Partition[PrimeOmega[Range[700]],3,1],_?(#[[1]]==#[[2]]+#[[3]] &),1,Heads->False]//Flatten (* _Harvey P. Dale_, Aug 18 2019 *)
%o A077617 (PARI) j=[]; for(n=1,1000,if(bigomega(n)==bigomega(n+1)+bigomega(n+2),j=concat(j,n))); j
%o A077617 (Magma) f:=func<n|&+[p[2]: p in Factorization(n)]>; [k:k in [2..650]| f(k) eq f(k+1)+ f(k+2)]; // _Marius A. Burtea_, Feb 19 2020
%Y A077617 Cf. A001222, A076136.
%K A077617 nonn
%O A077617 1,1
%A A077617 _Shyam Sunder Gupta_, Dec 01 2002