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.
%I A266816 #19 May 16 2019 08:53:28 %S A266816 4,11,25,329,3383,4343,5561,6623,12773,17267,21479,57721,129383, %T A266816 136259,142943,172793,256631,292571,364823,413663,413927,619337, %U A266816 653291,1215659,1218863,1268951,1276931,1483751,1655219,1892327,2952731,4158719,4973531,5418671,6377663 %N A266816 Numbers whose arithmetic derivative is equal to the product of their digits. %C A266816 4 appears to be the only even number in the sequence. %H A266816 Paolo P. Lava, <a href="/A266816/b266816.txt">Table of n, a(n) for n = 1..100</a> %e A266816 4’ = 4; %e A266816 11’ = 1 = 1*1; %e A266816 25’ = 10 = 2*5; %e A266816 329’ = 54 = 3*2*9; etc. %p A266816 with(numtheory): P:=proc(q) local a,b,k,n; for n from 1 to q do a:=n; b:=1; %p A266816 for k from 1 to ilog10(n)+1 do b:=b*(a mod 10); a:=trunc(a/10); od; %p A266816 if n*add(op(2,a)/op(1,a),a=ifactors(n)[2])=b then print(n); fi; od; end: P(10^9); %t A266816 Select[Range[3, 10^5], Times @@ IntegerDigits@ # == # Total[#2/#1 & @@@ %t A266816 FactorInteger@ Abs@ #] &] (* _Michael De Vlieger_, Feb 10 2016, after _Michael Somos_ at A003415 *) %Y A266816 Cf. A003415, A007954, A058627, A145746. %K A266816 nonn,base %O A266816 1,1 %A A266816 _Paolo P. Lava_, Feb 10 2016