This site is supported by donations to The OEIS Foundation.

 Annual appeal: Please make a donation to keep the OEIS running! Over 6000 articles have referenced us, often saying "we discovered this result with the help of the OEIS". Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A058254 a(n) = lcm{prime(i)-1, i=1..n}. 7
 1, 2, 4, 12, 60, 60, 240, 720, 7920, 55440, 55440, 55440, 55440, 55440, 1275120, 16576560, 480720240, 480720240, 480720240, 480720240, 480720240, 480720240, 19709529840, 19709529840, 39419059680, 197095298400, 3350620072800 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS A002110(n) divides b^(a(n)+1) - b for every integer b. - Thomas Ordowski, Nov 24 2014 What is the asymptotic growth of this sequence? a(n) <= A005867(n) <= A002110(n) < e^((1 + o(1))n log n) but this is a large overestimate. - Charles R Greathouse IV, Dec 03 2014 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..1000 FORMULA a(n) = A002322(A002110(n)). - Thomas Ordowski, Nov 24 2014 EXAMPLE For n = 5 and 6: a(5) = a(6) = LCM[1, 2, 4, 6, 10, 12] = 60. MAPLE seq(ilcm(seq(ithprime(i)-1, i=1..n)), n=1..100); # Robert Israel, Nov 24 2014 MATHEMATICA Table[LCM @@ (Prime@ Range[1, n] - 1), {n, 27}] (* Michael De Vlieger, Dec 31 2016 *) PROG (Haskell) a058254 n = a058254_list !! (n-1) a058254_list = scanl1 lcm a006093_list -- Reinhard Zumkeller, May 01 2013 (PARI) a(n)=lcm(apply(p->p-1, primes(n))) \\ Charles R Greathouse IV, Dec 03 2014 CROSSREFS Cf. A000010, A000142, A002110, A003418, A005867, A006093, A055769, A058255. Sequence in context: A128648 A128646 A155747 * A076244 A058255 A118456 Adjacent sequences:  A058251 A058252 A058253 * A058255 A058256 A058257 KEYWORD nonn AUTHOR Labos Elemer, Dec 06 2000 EXTENSIONS Offset corrected by Reinhard Zumkeller, May 01 2013 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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.