A325177 Unitary highly touchable numbers: Numbers m > 1 such that a record number of numbers k have m as the sum of the proper unitary divisors of k.

2, 6, 8, 12, 22, 33, 49, 55, 67, 79, 91, 115, 121, 151, 169, 175, 181, 211, 295, 301, 361, 391, 421, 481, 511, 571, 631, 781, 841, 991, 1051, 1171, 1231, 1261, 1321, 1471, 1561, 1681, 1891, 2101, 2311, 2731, 3151, 3361, 3571, 3991, 4201, 4291, 4411, 4621, 5251

Offset

1,1

Comments

The unitary version of A238895.

Links

Amiram Eldar, Table of n, a(n) for n = 1..78

Amiram Eldar, Table of n, a(n), A324938(a(n)) for n = 1..78

Mathematica

us[1] = 0; us[n_] := Times @@ (1 + Power @@@ FactorInteger[n]) - n;  m = 300; v = Table[0, {m}]; Do[u = us[k]; If[2 <= u <= m, v[[u]]++], {k, 1, m^2}]; s = {}; vm = -1; Do[If[v[[k]] > vm, vm = v[[k]]; AppendTo[s, k]], {k, 2, m}]; s

Crossrefs

Cf. A034448, A034460, A063948, A238895, A324938.

Sequence in context: A177869 A138639 A082473 * A263312 A346587 A226818

Adjacent sequences: A325174 A325175 A325176 * A325178 A325179 A325180

Keyword

nonn

Author

Amiram Eldar, Sep 05 2019

Status

approved