A362186 a(n) is the least number k such that the equation A323410(x) = k has exactly n solutions, or -1 if no such k exists.

2, 0, 6, 10, 20, 31, 47, 53, 65, 77, 89, 113, 125, 119, 149, 173, 167, 179, 233, 279, 239, 209, 439, 293, 365, 299, 329, 359, 455, 521, 467, 389, 461, 419, 479, 773, 539, 509, 599, 845, 671, 791, 749, 719, 659, 629, 809, 1055, 881, 779, 899, 965, 929, 1121, 839, 1403

Offset

0,1

Comments

Is there any n for which a(n) = -1?

Links

Amiram Eldar, Table of n, a(n) for n = 0..1292

Formula

A362181(a(n)) = n.

Mathematica

ucototient[n_] := n - Times @@ (Power @@@ FactorInteger[n] - 1); ucototient[1] = 0; With[{max = 300}, solnum = Table[0, {n, 1, max}]; Do[If[(i = ucototient[k]) <= max, solnum[[i]]++], {k, 2, max^2}]; Join[{2, 0}, TakeWhile[FirstPosition[ solnum, #] & /@ Range[2, max] // Flatten, NumberQ]]]

Crossrefs

The unitary version of A063507.

Cf. A323410, A362181.

Similar sequences: A007374, A361970.

Sequence in context: A011123 A087464 A078048 * A335061 A350462 A357367

Adjacent sequences: A362183 A362184 A362185 * A362187 A362188 A362189

Keyword

nonn

Author

Amiram Eldar, Apr 10 2023

Status

approved