A348073 - OEIS

%I #30 Jul 19 2023 07:46:30

%S 223092870,281291010,300690390,340510170,358888530,363993630,

%T 380570190,397687290,406816410,417086670,434444010,446185740,

%U 455885430,458948490,481410930,485555070,497668710,504894390,512942430,514083570,531990690,538047510,547777230,551861310,562582020

%N Numbers k such that omega(k) = 9.

%H David A. Corneth, <a href="/A348073/b348073.txt">Table of n, a(n) for n = 1..10000</a>

%e 562582020 = 2^2 * 3 * 5 * 7 * 11 * 13 * 17 * 19 * 29 is in the sequence as it has 9 distinct prime divisors (namely 2, 3, 5, 7, 11, 13, 17, 19 and 29).

%o (PARI) is(n) = omega(n) == 9

%o (PARI) A246655(lim)=my(v=List(primes([2,lim\=1]))); for(e=2,logint(lim,2), forprime(p=2,sqrtnint(lim,e), listput(v,p^e))); Set(v)

%o list(lim,pr=9)=if(pr==1, return(A246655(lim))); my(v=List(),pr1=pr-1,mx=prod(i=1,pr1,prime(i))); forprime(p=prime(pr),lim\mx, my(u=list(lim\p,pr1)); for(i=1,#u,listput(v,p*u[i]))); Set(v) \\ _Charles R Greathouse IV_, Feb 03 2023

%Y Row 9 of A125666.

%Y Cf. A001221, A046312.

%K nonn

%O 1,1

%A _David A. Corneth_, Oct 10 2021