This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A104875 Semiprimes of the form prime(n)*prime(n+1)*prime(n+2)*prime(n+3)*prime(n+4) - 1. 3
 15014, 1062346, 600662302, 2224636919002, 118335570521086, 168652154886862, 3790374062238502, 6290838589498366, 127018534712243098, 131125107904515418, 190740905520325018, 2057351971883521282, 3151949824862998762 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS This is the five-consecutive-prime minus one equivalent of A103533. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE n prime(n) * prime(n+1) * prime(n+2) * prime(n+3) * prime(n+4) - 1 1: 2 * 3 * 5 * 7 * 11 - 1 = 2309 is prime; examples hereafter are semiprime 2: 3 * 5 * 7 * 11 * 13 - 1 = 15014 = 2 * 7507 5: 11 * 13 * 17 * 19 * 23 - 1 = 1062346 = 2 * 531173 15: 47 * 53 * 59 * 61 * 67 - 1 = 600662302 = 2 * 300331151 60: 281 * 283 * 293 * 307 * 311 - 1 = 2224636919002 = 2 * 1112318459501 117: 643 * 647 * 653 * 659 * 661 - 1 = 118335570521086 = 2 * 59167785260543 MATHEMATICA Bigomega[n_]:=Plus@@Last/@FactorInteger[n]; SemiprimeQ[n_]:=Bigomega[n]==2; Select[Table[Prime[n]*Prime[n+1]*Prime[n+2]*Prime[n+3]*Prime[n+4]-1, {n, 1000}], SemiprimeQ] (*Chandler*) CROSSREFS Cf. A000040, A001358, A006881, A103533, A103614, A103746, A104874. Sequence in context: A064730 A081635 A165614 * A046391 A112643 A129485 Adjacent sequences:  A104872 A104873 A104874 * A104876 A104877 A104878 KEYWORD easy,nonn AUTHOR Jonathan Vos Post, Mar 29 2005 EXTENSIONS Extended by Ray Chandler Mar 29 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 | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified March 23 18:13 EDT 2019. Contains 321433 sequences. (Running on oeis4.)