A362666 - OEIS

%I #7 Apr 29 2023 07:36:29

%S 2,6,8,10,0,24,0,30,0,22,0,42,0,0,32,54,0,56,0,66,0,46,0,120,0,0,0,58,

%T 0,96,0,102,0,0,0,168,0,0,0,110,0,86,0,138,128,94,0,216,0,0,0,106,0,

%U 152,0,174,0,118,0,264,0,0,0,270,0,184,0,0,0,142,0,312

%N a(n) is the largest m such that iphi(m) = n, where iphi is the infinitary totient function A091732, or a(n) = 0 if no such m exists.

%H Amiram Eldar, <a href="/A362666/b362666.txt">Table of n, a(n) for n = 1..10000</a>

%F a(A362486(n)) = 0.

%e a(1) = 2 since there are two solutions to iphi(x) = 1: 1 and 2, and 2 is the larger of them.

%e a(6) = 24 since there are four solutions to iphi(x) = 6: 7, 12, 14 and 24, and 24 is the largest of them.

%t a[n_] := If[(inv = invIPhi[n]) == {}, 0, Max[inv]]; Array[a, 100] (* using the function invIPhi from A362484 *)

%Y The infinitary version of A057635.

%Y Cf. A091732, A362484, A362486 (positions of 0's), A362667 (record values), A362668 (indices of records).

%K nonn

%O 1,1

%A _Amiram Eldar_, Apr 29 2023