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a(n) = the smallest numbers k such that A007955(k) = n, or 0 if there is no such k, where A007955(m) = product of divisors of m.
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%I #8 Aug 06 2024 02:09:44

%S 1,2,3,0,5,0,7,4,0,0,11,0,13,0,0,0,17,0,19,0,0,0,23,0,0,0,9,0,29,0,31,

%T 0,0,0,0,6,37,0,0,0,41,0,43,0,0,0,47,0,0,0,0,0,53,0,0,0,0,0,59,0,61,0,

%U 0,8,0,0,67,0,0,0,71,0,73,0,0,0,0,0,79,0,0,0,83

%N a(n) = the smallest numbers k such that A007955(k) = n, or 0 if there is no such k, where A007955(m) = product of divisors of m.

%C a(n) = the largest numbers k such that A007955 (k) = n, or 0 if there is no such k.

%H Amiram Eldar, <a href="/A174900/b174900.txt">Table of n, a(n) for n = 1..10000</a>

%t With[{m = 100}, s[n_] := n^(DivisorSigma[0, n]/2); (FirstPosition[Array[s, m], #] & /@ Range[m]) /. Missing["NotFound"] -> 0 // Flatten] (* _Amiram Eldar_, Aug 06 2024 *)

%Y Cf. A007955.

%K nonn

%O 1,2

%A _Jaroslav Krizek_, Apr 01 2010

%E More terms from _Amiram Eldar_, Aug 06 2024