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 A320522 #40 Oct 21 2023 19:55:55
%S A320522 1,10,20,25,40,50,64,80,100,125,128,160,200,250,256,320,400,500,512,
%T A320522 625,640,800,1000,1024,1250,1280,1600,2000,2048,2500,2560,3125,3200,
%U A320522 4000,4096,5000,5120,6250,6400,8000,8192,10000,10240,12500,12800,15625,16000
%N A320522 Numbers k such that k^10 divides 10^k.
%C A320522 The sequence consists of the numbers of the form 2^i*5^j (A003592) except for {2, 4, 5, 8, 16, 32}. - _Giovanni Resta_, Nov 13 2018
%e A320522 20 is in the sequence because 20^10 divides 10^20.
%e A320522 5 is not in the sequence because 5^10 does not divide 10^5.
%t A320522 Select[Union@ Flatten@ Table[2^a * 5^b, {a, 0, Log[2, #/(1)]}, {b, 0, Log[5, #/(2^a)]}] &[10^5], PowerMod[10, #, #^10] == 0 &] (* _Michael De Vlieger_, Oct 15 2018 *)
%t A320522 m = 10^5; DeleteCases[Union @@ Table[2^a*5^b, {a, 0, Log2@ m}, {b, Boole[0 < a < 6], Log[5, m/2^a]}], 5] (* _Giovanni Resta_, Nov 13 2018 *)
%o A320522 (PARI) isok(n) = Mod(10, n^10)^n == 0; \\ _Michel Marcus_, Oct 14 2018
%o A320522 (GAP) Filtered([1..16000],k->PowerMod(10,k,k^10)=0); # _Muniru A Asiru_, Oct 16 2018
%Y A320522 Subsequence of A003592 (numbers of the form 2^i*5^j).
%Y A320522 Cf. A008454 (n^10), A011557 (10^n),
%K A320522 nonn
%O A320522 1,2
%A A320522 _Kritsada Moomuang_, Oct 14 2018