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 A333598 #39 Oct 30 2023 11:07:22 %S A333598 0,1,2,3,4,5,6,7,8,9,10,11,12,14,22,30,37,44,57,63,69,70,81,86,91,106, %T A333598 111,116,126,131,140,145,154,163,168,177,186,199,221,225,238,242,255, %U A333598 259,288,292,368,372,384,388,407,411,419,423,438,450,532 %N A333598 Numbers m such that m! has a palindromic number of decimal digits. %C A333598 The corresponding palindromic numbers are 1, 1, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 22, 33, 44, 55, 77, 88, 99, 101, ... %C A333598 Nice result: 22 is a palindrome and 22! has 22 digits, and also, 44! has 55 digits. %e A333598 14! = 87178291200 that has 11 digits, 11 is a palindrome, hence 14 is a term. %t A333598 Select[Range[0, 532], PalindromeQ @ Length @ IntegerDigits[#!] &] (* _Amiram Eldar_, Mar 28 2020 *) %t A333598 Select[Range[0,550],PalindromeQ[IntegerLength[#!]]&] (* _Harvey P. Dale_, Oct 30 2023 *) %o A333598 (PARI) isok(m) = my(d=digits(#Str(m!))); d == Vecrev(d); \\ _Michel Marcus_, Mar 28 2020 %Y A333598 Cf. A000142, A002113, A034886. %Y A333598 Cf. A006488 (similar, with square), A035065 (similar, with prime), A056851 (similar, with cube), A333431 (similar, with factorial). %K A333598 nonn,base %O A333598 1,3 %A A333598 _Bernard Schott_, Mar 28 2020