cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A064354 Distinct values arising in the sequence of the least common multiples of the first n composite numbers.

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%I A064354 #17 Dec 06 2018 16:56:06
%S A064354 1,4,12,24,72,360,2520,5040,55440,277200,3603600,10810800,21621600,
%T A064354 367567200,6983776800,160626866400,1124388064800,32607253879200,
%U A064354 1010824870255200,2021649740510400,74801040398884800,224403121196654400
%N A064354 Distinct values arising in the sequence of the least common multiples of the first n composite numbers.
%H A064354 Harry J. Smith, <a href="/A064354/b064354.txt">Table of n, a(n) for n = 1..100</a>
%e A064354 Different from A003418 and A051451.
%t A064354 t=t=Select[ Range[ 1, 200 ], !PrimeQ[ # ] & ] Union[ Table[ Apply[ LCM, Table[ Part[ t, w ], {w, 1, s} ] ], {s, 1, 100} ] ]
%t A064354 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 A064354 (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 A064354 Cf. A002808, A003418, A051451, A025543.
%K A064354 nonn
%O A064354 1,2
%A A064354 _Labos Elemer_, Sep 25 2001
%E A064354 a(22) from _Harry J. Smith_, Sep 12 2009
%E A064354 Definition clarified by _Harvey P. Dale_, Dec 06 2018