A066616 - OEIS

%I #16 Jul 12 2022 14:36:04

%S 1,2,6,24,120,120,840,840,7560,7560,83160,83160,1081080,1081080,

%T 1081080,17297280,294053760,294053760,5587021440,5587021440,

%U 5587021440,5587021440,128501493120,128501493120,3212537328000,3212537328000

%N a(1) = 1; a(n) = n*a(n-1) if n does not divide a(n-1), otherwise a(n) = a(n-1).

%H Harry J. Smith, <a href="/A066616/b066616.txt">Table of n, a(n) for n = 1..200</a>

%F a(1) = 1; for n > 1, a(n) = A059896(a(n-1), n). - _Peter Munn_, Jul 12 2022

%e a(5) = 120; as 6 divides a(5), we have a(6) = a(5) = 120. Though 9 is not coprime to a(8) but still 9 does not divide a(8) so a(9) = 9 * a(8).

%t nxt[{n_,a_}]:={n+1,If[Mod[a,n+1]==0,a,a(n+1)]}; NestList[nxt,{1,1},30][[All,2]] (* _Harvey P. Dale_, Jul 01 2022 *)

%o (PARI) { for (n=1, 200, if (n==1, a=1, if (a%n, a=n*a)); write("b066616.txt", n, " ", a) ) } \\ _Harry J. Smith_, Mar 12 2010

%Y Cf. A003418, A037992 (duplicates removed).

%Y Replacing A059896 with A059897 in the formula gives A284567.

%K nonn

%O 1,2

%A _Amarnath Murthy_, Dec 24 2001

%E More terms from _Vladeta Jovovic_, Dec 26 2001