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A260656 a(n) = lcm{!2, !3, ..., !n}, where !n = A000166(n) is subfactorial. 1

%I #23 May 08 2020 22:55:33

%S 1,2,18,396,104940,10808820,160327227060,486432806900040,

%T 72152091814676033160,105952244289903723626034120,

%U 1697305261921685687642685992397720,108004858262683508632706244802225075247640,266448824855803491635798907952730108331437779905720

%N a(n) = lcm{!2, !3, ..., !n}, where !n = A000166(n) is subfactorial.

%C a(n) <= A131631(n).

%H Alois P. Heinz, <a href="/A260656/b260656.txt">Table of n, a(n) for n = 2..45</a>

%H <a href="/index/Lc#lcm">Index entries for sequences related to lcm's</a>

%e For n = 5, a(5) = lcm(!2, !3, !4, !5) = lcm(1, 2, 9, 44) = 396.

%p b:= proc(n) option remember;

%p `if`(n=0, 1, n*b(n-1)+(-1)^n)

%p end:

%p a:= n-> ilcm(seq(b(i), i=2..n)):

%p seq(a(n), n=2..15); # _Alois P. Heinz_, May 08 2020

%t LCM@@@Subfactorial@Range[2, Range[2, 14]]

%o (PARI) a(n) = lcm(vector(n-1, k, if(k+1,round((k+1)!/exp(1)),1))); \\ _Altug Alkan_, Nov 13 2015

%Y Cf. A000166, A131631.

%K nonn

%O 2,2

%A _Vladimir Reshetnikov_, Nov 13 2015

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Last modified March 29 05:16 EDT 2024. Contains 371264 sequences. (Running on oeis4.)