cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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

This page as a plain text file.
%I A036924 #26 Aug 25 2024 16:38:21
%S A036924 4,22,58,94,166,202,274,346,378,382,438,454,526,562,576,588,634,636,
%T A036924 648,654,666,690,706,728,762,778,852,922,958,1086,1282,1284,1376,1626,
%U A036924 1642,1678,1736,1776,1822,1842,1858,1872,1894,1908,1952,1962,1966,2038
%N A036924 Digit sum of composite even number equals digit sum of juxtaposition of its prime factors (counted with multiplicity).
%C A036924 Even Smith numbers. - _Robert Israel_, Aug 24 2024
%H A036924 Robert Israel, <a href="/A036924/b036924.txt">Table of n, a(n) for n = 1..10000</a>
%p A036924 filter:= proc(n) local F;
%p A036924   F:= ifactors(n)[2];
%p A036924   convert(convert(n,base,10),`+`) = convert(map(t -> t[2]*convert(convert(t[1],base,10),`+`), F),`+`)
%p A036924 end proc:
%p A036924 select(filter, [seq(i,i=4..10000,2)]); # _Robert Israel_, Aug 24 2024
%t A036924 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 *)
%Y A036924 Cf. A006753, A019506, A036925.
%K A036924 nonn,base
%O A036924 1,1
%A A036924 _Patrick De Geest_, Jan 04 1999
%E A036924 Title made more precise by _Sean A. Irvine_, Nov 30 2020