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 A173345 #26 Feb 16 2025 08:33:12
%S A173345 0,0,0,0,1,2,3,4,5,7,9,11,13,15,18,21,24,27,30,34,38,42,46,50,56,62,
%T A173345 68,74,80,87,94,101,108,115,123,131,139,147,155,164,173,182,191,200,
%U A173345 210,220,230,240,250,262,274,286,298,310,323,336,349,362,375,389,403,417
%N A173345 Number of trailing zeros of the superfactorial of n (A000178).
%H A173345 Andrew Howroyd, <a href="/A173345/b173345.txt">Table of n, a(n) for n = 1..1000</a>
%H A173345 A. M. Oller-Marcen and J. Maria Grau, <a href="https://cs.uwaterloo.ca/journals/JIS/VOL14/Oller/oller3.html">On the Base-b Expansion of the Number of Trailing Zeros of b^k!</a>, J. Int. Seq. 14 (2011), Article 11.6.8.
%H A173345 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/Superfactorial.html">Superfactorial</a>.
%F A173345 a(n) = Sum_{k=1..n} A027868(k). - _Charles R Greathouse IV_, Jun 10 2011
%t A173345 a[n_] := Sum[Z10[i], {i, n}]; Z10[n_]:= Floor[Sum[Floor[n/5^i], {i, 1, Floor[Log[5, n]]}]]; Join[{0},Table[a[n], {n, 2, 200}]]
%t A173345 a[0] := 1; a[1] := 1; a[n_] := n!*a[n - 1];IntegerExponent[Table[a[n], {n, 1, 100}]] (* _Stefano Spezia_, Jan 26 2023 *)
%o A173345 (PARI) a(n)=my(t=0);sum(k=5,n,t+=valuation(k,5)) \\ _Charles R Greathouse IV_, Jun 10 2011
%Y A173345 Cf. A000178, A027868.
%K A173345 easy,base,nonn
%O A173345 1,6
%A A173345 _José María Grau Ribas_, Feb 16 2010