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 A033180 #47 Aug 05 2025 13:35:43 %S A033180 1,2,4,20,21,26,30,33,37,39,42,44,45,48,51,52,53,56,59,60,64,65,67,68, %T A033180 69,72,75,78,79,80,81,82,83,84,88,91,93,94,95,96,97,98,99,116,124,134, %U A033180 136,140,141,149,164,165,166,170,174,180,186,188,196,198,200,202,205 %N A033180 Numbers k such that k! contains k as a string of digits. %H A033180 Mia Boudreau, <a href="/A033180/b033180.txt">Table of n, a(n) for n = 1..10000</a> (First 1000 terms from T. D. Noe) %H A033180 <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a> %F A033180 A067109(a(n)) > 0. - _Reinhard Zumkeller_, Aug 23 2008 %t A033180 Select[Range[210],MemberQ[Partition[IntegerDigits[#!],IntegerLength[#], 1], IntegerDigits[ #]]&] (* _Harvey P. Dale_, Dec 25 2011 *) %t A033180 Select[Range@500, StringContainsQ[ToString[#!], ToString[#]] &] (* _Ivan N. Ianakiev_, Jul 28 2016 *) %t A033180 Select[Range[210],SequenceCount[IntegerDigits[#!],IntegerDigits[#]]>0&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 14 2017 *) %o A033180 (Haskell) %o A033180 a033180 n = a033180_list !! (n-1) %o A033180 a033180_list = filter ((> 0) . a067109) [1..] %o A033180 -- _Reinhard Zumkeller_, Aug 28 2014 %o A033180 (Python) %o A033180 from math import factorial %o A033180 def ok(n): return str(n) in str(factorial(n)) %o A033180 print(list(filter(ok, range(206)))) # _Michael S. Branicky_, Aug 07 2021 %Y A033180 Cf. A000142, A067109. %K A033180 nonn,base,easy,nice %O A033180 1,2 %A A033180 _Jeff Burch_ %E A033180 More terms from _David W. Wilson_