A039945 Maris-McGwire numbers(2): numbers k such that f(k) = f(k+1), where f(k) = sum of digits of k + sum of digits of the distinct prime factors of k.

3, 12, 14, 45, 61, 118, 122, 124, 137, 143, 152, 213, 224, 225, 242, 273, 277, 356, 373, 390, 392, 398, 421, 428, 455, 457, 460, 462, 464, 510, 526, 537, 560, 590, 607, 621, 673, 680, 692, 746, 782, 797, 804, 818, 820, 866, 878, 922, 939, 944, 965, 980, 985

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A045759.

Programs

Mathematica

ds[n_] := Plus @@ IntegerDigits[n]; f[n_] := ds[n] + Total[ds /@ FactorInteger[n][[;; , 1]]]; s = {}; f1 = 1; Do[f2 = f[n]; If[f1 == f2, AppendTo[s, n-1]]; f1 = f2, {n, 2, 1000}]; s (* Amiram Eldar, Nov 24 2019 *)
SequencePosition[Flatten[Table[Total[IntegerDigits[n]]+Total[Flatten[IntegerDigits/@FactorInteger[n][[All,1]]]],{n,1000}]],{x_,x_}][[All,1]](* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jan 09 2021 *)