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 A104355 #23 Apr 09 2024 09:24:31
%S A104355 0,0,0,0,1,1,1,1,1,2,2,2,2,2,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,
%T A104355 5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,
%U A104355 6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6
%N A104355 Number of trailing zeros in decimal representation of A104350(n).
%H A104355 Amiram Eldar, <a href="/A104355/b104355.txt">Table of n, a(n) for n = 1..10000</a>
%H A104355 David A. Corneth, <a href="/A104355/a104355.gp.txt">PARI link</a>
%H A104355 Reinhard Zumkeller, <a href="/A104350/a104350.txt">Products of largest prime factors of numbers <= n</a>.
%F A104355 a(A104356(n)) = n and a(m) < n for m < A104356(n);
%F A104355 a(n) = A122840(A104350(n)). - _Reinhard Zumkeller_, Mar 10 2013
%t A104355 IntegerExponent[FoldList[Times, Array[FactorInteger[#][[-1, 1]] &, 100]], 10] (* _Amiram Eldar_, Apr 08 2024 *)
%o A104355 (PARI) gpf(n) = {my(p = factor(n)[, 1]); p[#p];}
%o A104355 a(n) = valuation(prod(k = 2, n, gpf(k)), 10); \\ _Amiram Eldar_, Apr 08 2024
%o A104355 (PARI) \\ See link. _David A. Corneth_, Apr 08 2024
%Y A104355 Cf. A000079, A027868, A080193, A104350, A104356, A122840.
%K A104355 nonn,base
%O A104355 1,10
%A A104355 _Reinhard Zumkeller_, Mar 06 2005