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A362229 a(n) is the largest m such that uphi(m) = n, where uphi is the unitary totient function (A047994), or a(n) = 0 if no such m exists.

%I A362229 #12 Apr 13 2023 02:35:48
%S A362229 2,6,4,10,0,14,8,30,0,22,0,42,0,24,16,34,0,38,0,66,0,46,0,78,0,54,0,
%T A362229 58,0,62,32,102,0,0,0,114,0,0,0,110,0,86,0,138,0,94,0,210,0,0,0,106,0,
%U A362229 76,0,174,0,118,0,186,0,96,64,170,0,134,0,0,0,142,0,222
%N A362229 a(n) is the largest m such that uphi(m) = n, where uphi is the unitary totient function (A047994), or a(n) = 0 if no such m exists.
%H A362229 Amiram Eldar, <a href="/A362229/b362229.txt">Table of n, a(n) for n = 1..10000</a>
%F A362229 a(A347771(n)) = 0.
%e A362229 a(1) = 2 since there are two solutions to uphi(x) = 1: 1 and 2, and 2 is the larger of them.
%e A362229 a(6) = 14 since there are three solutions to uphi(x) = 6: 7, 12 and 14, and 14 is the largest of them.
%t A362229 a[n_] := If[(inv = invUPhi[n]) == {}, 0, Max[inv]]; Array[a, 100] (* using the function invUPhi from A361966 *)
%Y A362229 The unitary version of A057635.
%Y A362229 Cf. A047994, A347771 (positions of 0's), A361966, A362230 (record values), A362231 (indices of records).
%K A362229 nonn
%O A362229 1,1
%A A362229 _Amiram Eldar_, Apr 12 2023