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A131134
a(1)=1. a(n) = (1/n + 1/a(n-1)) * lcm(n,a(n-1)).
3
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
1,2
LINKS
FORMULA
For n > 1: a(n) = (n + a(n-1)) / GCD(n, a(n-1)). - 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 *)
PROG
(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
CROSSREFS
Cf. A131133.
Equals T(n+1,2) for the Adams-Watters triangle, A125605. - Gerry Myerson, Mar 18 2010
Sequence in context: A123649 A080848 A016602 * A151690 A346472 A288247
KEYWORD
nonn
AUTHOR
Leroy Quet, Jun 17 2007
EXTENSIONS
More terms from R. J. Mathar, Oct 17 2007
STATUS
approved