A131134 a(1)=1. a(n) = (1/n + 1/a(n-1)) * lcm(n,a(n-1)).

1, 3, 2, 3, 8, 7, 2, 5, 14, 12, 23, 35, 48, 31, 46, 31, 48, 11, 30, 5, 26, 24, 47, 71, 96, 61, 88, 29, 2, 16, 47, 79, 112, 73, 108, 4, 41, 79, 118, 79, 120, 27, 70, 57, 34, 40, 87, 45, 94, 72, 41, 93, 146, 100, 31, 87, 48, 53, 112, 43, 104, 83, 146, 105, 34, 50, 117, 185, 254

Offset: 1

Author

Leroy Quet, Jun 17 2007

Keywords

• nonn

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A131133.

Equals T(n+1,2) for the Adams-Watters triangle, A125605. - Gerry Myerson, Mar 18 2010

Programs

Haskell

a131134 n = a131134_list !! (n-1)
a131134_list = 1 : zipWith (\v w -> (v+w) `div` gcd v w) [2..] a131134_list
-- Reinhard Zumkeller, Nov 26 2015

Maple

A131134 := proc(n) option remember ; if n = 1 then 1; else (1/n+1/A131134(n-1))*lcm(n,A131134(n-1)) ; fi ; end: seq(A131134(n),n=1..80) ; # R. J. Mathar, Oct 17 2007

Mathematica

nxt[{n_,a_}]:={n+1,(1/(n+1)+1/a)LCM[n+1,a]}; Transpose[NestList[nxt,{1,1},70]][[2]] (* Harvey P. Dale, Aug 13 2013 *)

Formula

For n > 1: a(n) = (n + a(n-1)) / GCD(n, a(n-1)). - Reinhard Zumkeller, Nov 26 2015

Extensions

More terms from R. J. Mathar, Oct 17 2007