login
a(n) = the smallest (n+k) such that the LCM of numbers from (n+1) to (n+k) is a multiple of n.
6

%I #7 Dec 05 2013 19:56:01

%S 2,4,6,8,10,9,14,16,18,15,22,16,26,21,20,32,34,27,38,25,28,33,46,32,

%T 50,39,54,35,58,35,62,64,44,51,42,45,74,57,52,48,82,49,86,55,54,69,94,

%U 64,98,75,68,65,106,81,66,64,76,87,118,65,122,93,72,128,78,77,134,85,92,77

%N a(n) = the smallest (n+k) such that the LCM of numbers from (n+1) to (n+k) is a multiple of n.

%H Harvey P. Dale, <a href="/A081472/b081472.txt">Table of n, a(n) for n = 1..1000</a>

%e a(4) = 8 because lcm(5) = 5, lcm(5, 6) = 30 and lcm(5, 6, 7) = 210 are not divisible by 4, but lcm(5, 6, 7, 8) = 840 is.

%t dv[n_]:=Module[{k=1},While[!Divisible[LCM@@Range[n+1,n+k],n],k++];k+n]; Array[dv,70] (* _Harvey P. Dale_, Sep 13 2013 *)

%Y Cf. A081467, A081468, A081469, A081470, A081471, A061243.

%Y a(n) = n + A034699(n)

%K nonn

%O 1,1

%A _Amarnath Murthy_, Mar 23 2003

%E More terms from _David Wasserman_, Mar 24 2003