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 A355497 #86 Jul 17 2022 16:09:13
%S A355497 0,4,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,
%T A355497 31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,
%U A355497 54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80
%N A355497 Numbers k such that x^2 - s*x + p has only integer roots, where s and p denote the sum and product of the digits of k respectively.
%C A355497 All 2-digit numbers are terms.
%C A355497 All numbers having 0 as a digit (A011540) are terms, because p = 0, x^2 - s*x + p = x*(x-s) and the roots 0 and s are integers.
%H A355497 Jean-Marc Rebert, <a href="/A355497/b355497.txt">Table of n, a(n) for n = 1..3002</a>
%F A355497 a(n) = n + O(n^k) where k = log(9)/log(10) = 0.95424.... - _Charles R Greathouse IV_, Jul 07 2022
%e A355497 k = 14 is a term, since the sum of the digits of 14 is 5, the product of the digits of 14 is 4 and the roots 1 and 4 of x^2 - 5x + 4 are all integers.
%t A355497 kmax=80;kdig:=IntegerDigits[k]; s:=Total[kdig]; p:=Product[Part[kdig,i],{i,Length[kdig]}]; a:={};For[k=0,k<=kmax,k++,If[Element[x/.Solve[x^2-s*x+p==0,x],Integers],AppendTo[a,k]]]; a (* _Stefano Spezia_, Jul 06 2022 *)
%o A355497 (PARI) is(n)=my(v=if(n,digits(n),[0])); issquare(vecsum(v)^2-4*vecprod(v))
%Y A355497 Complement of A355547. A011540 is a subsequence.
%Y A355497 Cf. A007953, A007954, A355574 (number of n-digit terms).
%K A355497 nonn,base
%O A355497 1,2
%A A355497 _Jean-Marc Rebert_, Jul 04 2022