A039945 - OEIS

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

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

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

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 *)

CROSSREFS

Cf. A045759.

Sequence in context: A242130 A286386 A032918 * A227302 A201273 A221920

Adjacent sequences: A039942 A039943 A039944 * A039946 A039947 A039948

KEYWORD

nonn,base

AUTHOR

David W. Wilson

STATUS

approved