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Products of terms of A003418.
4

%I #21 May 09 2021 12:48:28

%S 1,2,4,6,8,12,16,24,32,36,48,60,64,72,96,120,128,144,192,216,240,256,

%T 288,360,384,420,432,480,512,576,720,768,840,864,960,1024,1152,1296,

%U 1440,1536,1680,1728,1920,2048,2160,2304,2520,2592,2880,3072,3360,3456

%N Products of terms of A003418.

%C Includes all factorials and Jordan-Polya numbers, since n! = Product_{i = 1..n} A003418(floor(n/i)) for positive n.

%H Michel Marcus, <a href="/A250270/b250270.txt">Table of n, a(n) for n = 1..5000</a>

%e 720 = 2*6*60 = 12*60. Since 2, 6, 12 and 60 are all terms of A003418, 720 is a term of this sequence.

%o (PARI) f(n) = lcm(vector(n, i, i)); \\ A003418

%o mul(x,y) = x*y;

%o lista(nn) = {my(v = vector(nn, k, f(k)), lim = f(nn+1), ok = 0, nv); while (!ok, nv = select(x->(x<lim), setbinop(mul, v)); ok = (#v == #nv); v = nv;); v;}

%o lista(30); \\ to get 5000 terms; _Michel Marcus_, May 09 2021

%Y Range of values of A253139. Subsequences include A000142, A001013, A001813, A025527, A064350, A166338, A250569.

%Y Subsequence of A025487.

%K nonn

%O 1,2

%A _Matthew Vandermast_, Dec 16 2014