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 A333421 #16 Mar 21 2020 07:13:27 %S A333421 3,7,11,41,127,139,173,179,191,751,811,5113,5167,5419,5443,6581,6659, %T A333421 6737,6761,6833,6863,6911,6959,40609,40897,41047,41479,42061,42349, %U A333421 42499,42643,42787,50549,51131,51419,51563,52289,52433,52583,52727,363361,363481,365473 %N A333421 Primes that are palindromic in factorial base. %H A333421 Amiram Eldar, <a href="/A333421/b333421.txt">Table of n, a(n) for n = 1..10000</a> %H A333421 Wikipedia, <a href="http://en.wikipedia.org/wiki/Factorial_number_system">Factorial number system</a>. %H A333421 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>. %e A333421 3 is a term since it is a prime number and its factorial base representation is 11 which is a palindrome. %t A333421 max = 9; Select[Range[0, max! - 1], PrimeQ[#] && PalindromeQ @ IntegerDigits[#, MixedRadix[Range[max, 2, -1]]] &] %Y A333421 Intersection of A000040 and A046807. %Y A333421 Cf. A007623, A108731. %Y A333421 Cf. A002385, A016041, A029971, A029972, A029973, A029974, A029975, A029976, A029977, A029978, A029979, A029980, A029981, A029982. %K A333421 nonn %O A333421 1,1 %A A333421 _Amiram Eldar_, Mar 20 2020