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!)
A110227 4-almost primes p * q * r * s relatively prime to p + q + r + s. 12
40, 54, 56, 88, 90, 104, 135, 136, 152, 184, 189, 198, 210, 225, 232, 248, 250, 294, 296, 297, 306, 328, 344, 350, 351, 376, 390, 414, 424, 441, 459, 462, 472, 488, 513, 522, 536, 546, 550, 568, 570, 584, 621, 632, 664, 686, 712, 714, 735, 738, 765, 776 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
p, q, r, s are not necessarily distinct. The converse to this is A110228: 4-almost primes p * q * r * s not relatively prime to p+q+r+s.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
EXAMPLE
104 is in this sequence because 104 = 2^3 * 13, which is relatively prime to 2 + 2 + 2 + 13 = 19, which is prime.
PROG
(PARI) list(lim)=my(v=List()); forprime(p=2, lim\8, forprime(q=2, min(p, lim\4\p), my(pq=p*q); forprime(r=2, min(lim\pq\2, q), my(pqr=pq*r, t); forprime(s=2, min(lim\pqr, r), t=pqr*s; if(gcd(t, p+q+r+s)==1, listput(v, t)))))); Set(v) \\ Charles R Greathouse IV, Jan 31 2017
CROSSREFS
Sequence in context: A217729 A255392 A116299 * A108607 A356744 A109730
KEYWORD
easy,nonn
AUTHOR
Jonathan Vos Post, Jul 16 2005
EXTENSIONS
Corrected and extended by Ray Chandler, Jul 20 2005
STATUS
approved

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 March 19 04:58 EDT 2024. Contains 370952 sequences. (Running on oeis4.)