A117570 - OEIS

%I #23 Nov 26 2024 13:27:19

%S 0,1,4,9,10,16,22,25,36,36,40,49,52,63,64,70,81,88,90,90,100,112,115,

%T 124,136,144,160,160,162,175,190,198,202,205,208,220,238,243,250,252,

%U 280,280,301,306,306,319,324,333,352,360,360,364,370,400,405,412,418,424

%N Numbers of the form k * (sum of digits of k) listed sorted with multiplicity.

%H David A. Corneth, <a href="/A117570/b117570.txt">Table of n, a(n) for n = 1..10000</a>

%H Ömer Eğecioğlu and Bünyamin Şahin, <a href="https://toc.ui.ac.ir/article_28781.html">On twin EP numbers</a>, Transact. Comb. (2025) Vol. 14, Iss. 4, Art. No. 4, 261-270. See p. 262.

%H Ernesto Estrada, Puri Pereira-Ramos, <a href="https://doi.org/10.1155/2018/9893867">Spatial 'Artistic' Networks: From Deconstructing Integer-Functions to Visual Arts</a>, Complexity, Vol. 2018 (2018), Article ID 9893867.

%e 2008 is a term since 2008 = 251*(2+5+1).

%t With[{nn = 400}, TakeWhile[#, # <= nn &] &@ Union@ Array[# Total@ IntegerDigits[#] &, nn + 1, 0]] (* _Michael De Vlieger_, Apr 19 2018 *)

%Y Sorted terms of A057147.

%Y Terms without duplicates are given by A337816.

%K nonn,base

%O 1,3

%A Ernesto Estrada (estrada66(AT)yahoo.com), Jan 02 2008