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Product of related numbers (counted in A073757) belonging to n; related = {divisor-set, RRS}: a(n) = A007955(n)*A001783(n).
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%I #14 Jun 20 2024 02:37:38

%S 1,2,6,24,120,180,5040,6720,60480,18900,39916800,665280,6227020800,

%T 3783780,201801600,2075673600,355687428096000,496215720,

%U 121645100408832000,69837768000,20858213376000,604969665300,25852016738884976640000,12336143339520,5170403347776995328000

%N Product of related numbers (counted in A073757) belonging to n; related = {divisor-set, RRS}: a(n) = A007955(n)*A001783(n).

%H Amiram Eldar, <a href="/A083267/b083267.txt">Table of n, a(n) for n = 1..450</a>

%e For n = 10: related terms = {1,2,5,10,3,7,9}, product = 1*2*5*10*1*3*7*9 = 18900 = a(10).

%t a[n_] := n^(DivisorSigma[0, n]/2) * Times@@ Select[Range[n], CoprimeQ[n, #] &]; Array[a, 30] (* _Amiram Eldar_, Jun 20 2024 *)

%Y Cf. A073757 (count), A083266 (sum), A083268 (LCM), A083267 (product), A001783, A007955.

%K nonn

%O 1,2

%A _Labos Elemer_, May 13 2003

%E More terms from _Amiram Eldar_, Jun 20 2024