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.

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, 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, 76, 0, 174, 0, 118, 0, 186, 0, 96, 64, 170, 0, 134, 0, 0, 0, 142, 0, 222

Offset: 1

Author

Amiram Eldar, Apr 12 2023

Keywords

• nonn

Examples

			a(1) = 2 since there are two solutions to uphi(x) = 1: 1 and 2, and 2 is the larger of them.
a(6) = 14 since there are three solutions to uphi(x) = 6: 7, 12 and 14, and 14 is the largest of them.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

The unitary version of A057635.

Cf. A047994, A347771 (positions of 0's), A361966, A362230 (record values), A362231 (indices of records).

Programs

Mathematica

a[n_] := If[(inv = invUPhi[n]) == {}, 0, Max[inv]]; Array[a, 100] (* using the function invUPhi from A361966 *)

Formula

a(A347771(n)) = 0.