A064354 - OEIS

%I #17 Dec 06 2018 16:56:06

%S 1,4,12,24,72,360,2520,5040,55440,277200,3603600,10810800,21621600,

%T 367567200,6983776800,160626866400,1124388064800,32607253879200,

%U 1010824870255200,2021649740510400,74801040398884800,224403121196654400

%N Distinct values arising in the sequence of the least common multiples of the first n composite numbers.

%H Harry J. Smith, <a href="/A064354/b064354.txt">Table of n, a(n) for n = 1..100</a>

%e Different from A003418 and A051451.

%t t=t=Select[ Range[ 1, 200 ], !PrimeQ[ # ] & ] Union[ Table[ Apply[ LCM, Table[ Part[ t, w ], {w, 1, s} ] ], {s, 1, 100} ] ]

%t Join[{1},With[{cmps=Select[Range[100],CompositeQ]},Table[LCM@@Take[cmps,n],{n,Length[cmps]}]]]//Union (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Dec 06 2018 *)

%o (PARI) { n=0; b=1; for (m=1, 10^9, if (m>1, if (isprime(m) || (b=lcm(a, m)) == a, next)); write("b064354.txt", n++, " ", a=b); if (n==100, break) ) } \\ _Harry J. Smith_, Sep 12 2009

%Y Cf. A002808, A003418, A051451, A025543.

%K nonn

%O 1,2

%A _Labos Elemer_, Sep 25 2001

%E a(22) from _Harry J. Smith_, Sep 12 2009

%E Definition clarified by _Harvey P. Dale_, Dec 06 2018