A036924 Digit sum of composite even number equals digit sum of juxtaposition of its prime factors (counted with multiplicity).

4, 22, 58, 94, 166, 202, 274, 346, 378, 382, 438, 454, 526, 562, 576, 588, 634, 636, 648, 654, 666, 690, 706, 728, 762, 778, 852, 922, 958, 1086, 1282, 1284, 1376, 1626, 1642, 1678, 1736, 1776, 1822, 1842, 1858, 1872, 1894, 1908, 1952, 1962, 1966, 2038

Offset

1,1

Comments

Even Smith numbers. - Robert Israel, Aug 24 2024

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Maple

filter:= proc(n) local F;
  F:= ifactors(n)[2];
  convert(convert(n, base, 10), `+`) = convert(map(t -> t[2]*convert(convert(t[1], base, 10), `+`), F), `+`)
end proc:
select(filter, [seq(i, i=4..10000, 2)]); # Robert Israel, Aug 24 2024

Mathematica

d[n_] := IntegerDigits[n]; co[n_, k_] := Nest[Flatten[d[{#, n}]]&, n, k-1]; t={}; Do[If[!PrimeQ[n] && Total[d[n]] == Total[Flatten[d[co@@@FactorInteger[n]]]], AppendTo[t, n]], {n, 4, 2040, 2}]; t (* Jayanta Basu, Jun 04 2013 *)

Crossrefs

Cf. A006753, A019506, A036925.

Sequence in context: A089761 A098837 A104171 * A130015 A189953 A174814

Adjacent sequences: A036921 A036922 A036923 * A036925 A036926 A036927

Keyword

nonn,base

Author

Patrick De Geest, Jan 04 1999

Extensions

Title made more precise by Sean A. Irvine, Nov 30 2020

Status

approved