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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A089581 a(n) = prime(2*n-1)*prime(2*n). 19
 6, 35, 143, 323, 667, 1147, 1763, 2491, 3599, 4757, 5767, 7387, 9797, 11021, 12317, 16637, 19043, 22499, 25591, 28891, 32399, 36863, 39203, 47053, 51983, 55687, 60491, 67591, 72899, 77837, 82919, 95477, 99221, 111547, 121103, 126727, 136891 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS a(n+1) is the smallest squarefree composite number that is relatively prime to the first 2*n prime numbers. Bisection of A006094. - R. J. Mathar, Jan 23 2013 LINKS Michael De Vlieger, Table of n, a(n) for n = 1..10000 FORMULA prime(2*n-1)*prime(2*n), n=1, 2, 3 ... EXAMPLE a(13)=9797 MATHEMATICA Table[Prime[2 n - 1] Prime[2 n], {n, 30}] (* Michael De Vlieger, Jul 21 2016 *) Times@@@Partition[Prime[Range[80]], 2] (* Harvey P. Dale, Jan 12 2022 *) PROG (PARI) p=2; q=3; i=1; a=vector(100); for(i=1, 100, a[i]=p*q; p=nextprime(q+1); q=nextprime(p+1)); a CROSSREFS Sequence in context: A094952 A024526 A213504 * A132657 A161784 A027985 Adjacent sequences: A089578 A089579 A089580 * A089582 A089583 A089584 KEYWORD easy,nonn AUTHOR Norbert A'Campo (nac(AT)member.ams.org), Dec 29 2003 EXTENSIONS Edited by Zak Seidov, Jun 13 2006 Typo in PARI program fixed by Zak Seidov, May 19 2010 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.

Last modified August 3 23:57 EDT 2024. Contains 374905 sequences. (Running on oeis4.)