login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A110232 6-almost primes p * q * r * s * t * u not relatively prime to p+q+r+s+t+u. 12

%I #8 Jan 31 2017 16:55:59

%S 64,144,160,216,240,324,336,400,528,540,560,624,729,756,784,816,840,

%T 880,900,912,1040,1104,1134,1188,1215,1232,1260,1320,1350,1360,1392,

%U 1404,1456,1488,1500,1520,1560,1764,1776,1836,1840,1848,1904,1936,1960,1968

%N 6-almost primes p * q * r * s * t * u not relatively prime to p+q+r+s+t+u.

%C p, q, r, s, t, u are not necessarily distinct. The converse to this is A110231: 6-almost primes p * q * r * s * t * u which are relatively prime to p+q+r+s+t+u. A046306 is the 6-almost primes.

%H Charles R Greathouse IV, <a href="/A110232/b110232.txt">Table of n, a(n) for n = 1..10000</a>

%e 160 is in this sequence because 160 = 2^5 * 5, the sum of whose prime factors is 2 + 2 + 2 + 2 + 2 + 5 = 15 = 3 * 5, which has a prime factor in common with 160.

%o (PARI) list(lim)=my(v=List()); forprime(p=2, lim\16, forprime(q=2, min(p, lim\8\p), my(pq=p*q); forprime(r=2, min(lim\pq\4, q), my(pqr=pq*r); forprime(s=2, min(lim\pqr\2, r), my(pqrs=pqr*s); forprime(t=2,min(lim\pqrs,s), my(pqrst=pqrs*t,n); forprime(u=2,min(lim\pqrst,t), n=pqrst*u; if(gcd(n, p+q+r+s+t+u)>1, listput(v, n)))))))); Set(v) \\ _Charles R Greathouse IV_, Jan 31 2017

%Y Cf. A046306, A110187, A110188, A110227, A110228, A110229, A110230, A110231, A110289, A110290, A110296, A110297.

%K easy,nonn

%O 1,1

%A _Jonathan Vos Post_, Jul 17 2005

%E Extended by _Ray Chandler_, Jul 20 2005

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 25 05:18 EDT 2024. Contains 371964 sequences. (Running on oeis4.)