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 A327324 #24 May 27 2025 18:21:44 %S A327324 1,2,3,4,5,7,333,17571,1757571,1787871,5136315,518686815,541626145, %T A327324 17575757571,5136813186315,5136868686315,5806270726085, %U A327324 172757272757271,513636363636315,17275787578757271,17578787578787571,17878787578787871,51363636363636315 %N A327324 Palindromes whose number and sum of divisors are both also palindromic. %C A327324 Numbers m such that m, A000005(m) = tau(m) and A000203(m) = sigma(m) are all in A002113. %C A327324 Corresponding values of tau(a(n)): 1, 2, 2, 3, 2, 2, 6, 4, 4, 4, 8, 8, 8, 4, 8, 8, 8, 4, 8, ... %C A327324 Corresponding values of sigma(a(n)): 1, 3, 4, 7, 6, 8, 494, 23432, 2343432, 2383832, ... %C A327324 Intersection of A028986 and A324988. %e A327324 tau(333) = A000005(333) = 6; sigma(333) = A000203(333) = 494. %t A327324 Select[Range[2*10^6], PalindromeQ[#] && PalindromeQ[DivisorSigma[0, #]] && PalindromeQ[DivisorSigma[1, #]] &] (* _Amiram Eldar_, Aug 31 2019 *) %o A327324 (Magma) [m: m in [1..1000000] | Intseq(m, 10) eq Reverse(Intseq(m, 10)) and Intseq(NumberOfDivisors(m), 10) eq Reverse(Intseq(NumberOfDivisors(m), 10)) and Intseq(&+[d: d in Divisors(m)], 10) eq Reverse(Intseq(&+[d: d in Divisors(m)], 10))]; %o A327324 (PARI) ispal(n) = my(d=digits(n)); d == Vecrev(d); %o A327324 isok(n) = ispal(n) && ispal(numdiv(n)) && ispal(sigma(n)); \\ _Michel Marcus_, Sep 02 2019 %Y A327324 Cf. A000005, A000203, A002113, A028986, A324989, A324988. %K A327324 nonn,base %O A327324 1,2 %A A327324 _Jaroslav Krizek_, Aug 30 2019 %E A327324 a(20)-a(23) with the help of _Daniel Suteu_