A078095 - OEIS

A078095

Numbers k such that Omega(k) = Omega(k-1) + Omega(k-2) + Omega(k-3) + Omega(k-4). (Omega(k) denotes the number of prime factors of k, counting multiplicity).

%I #10 Sep 08 2022 08:45:08

%S 1440,2560,2880,3456,3584,5760,6720,7168,8192,8448,9600,10080,10368,

%T 10800,12150,12480,13440,14000,15120,18144,21120,21384,22400,25088,

%U 25920,26880,28320,30240,31104,31680,34992,35840,38400,39168,39366

%N Numbers k such that Omega(k) = Omega(k-1) + Omega(k-2) + Omega(k-3) + Omega(k-4). (Omega(k) denotes the number of prime factors of k, counting multiplicity).

%H Amiram Eldar, <a href="/A078095/b078095.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 1440 is a term because Omega(1440) = 8 = Omega(1439) + Omega(1438) + Omega(1437) + Omega(1436) = 1 + 2 + 2 + 3 = 8.

%o (Magma) f:=func<n|&+[p[2]: p in Factorization(n)]>; [k:k in [6..40000]| f(k) eq f(k-1)+ f(k-2)+f(k-3)+f(k-4)]; // _Marius A. Burtea_, Feb 19 2020

%Y Cf. A001222.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Dec 01 2002