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 A359331 #18 Feb 17 2023 22:07:43
%S A359331 1,34,44,49,121,476,524,533,1808,6797,7326,10016,10201,10403,10817,
%T A359331 16019,17831,26322,33898,55198,57247,74711,87241,131395,148753,156029,
%U A359331 239593,240021,289831,295022,423758,441691,595777,725754,900009,2568543,2910271,2981619
%N A359331 Nonprime numbers k for which k*k' is a palindrome, where k' is the arithmetic derivative of k (A003415).
%e A359331 1*1' = 1*0 = 0, so 1 is a term.
%e A359331 34*34' = 34*19 = 646, so 34 is a term.
%e A359331 49*49' = 49*14 = 686, so 49 is a term.
%p A359331 d:= n-> n*add(i[2]/i[1], i=ifactors(n)[2]):
%p A359331 q:= n-> not isprime(n) and StringTools[IsPalindrome](""||(n*d(n))):
%p A359331 select(q, [$1..3000000])[]; # _Alois P. Heinz_, Jan 29 2023
%t A359331 d[0] = d[1] = 0; d[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); Select[Range[3*10^6], ! PrimeQ[#] && PalindromeQ[# * d[#]] &] (* _Amiram Eldar_, Jan 29 2023 *)
%o A359331 (Magma) f:=func<h |h le 1 select 0 else h*(&+[Factorisation(h)[i][2] /
%o A359331 Factorisation(h)[i][1]: i in [1..#Factorisation(h)]])>; pal:=func<n|Intseq(n) eq Reverse(Intseq(n))>; [n:n in [1..3000000]|not IsPrime(n) and pal(n*Floor(f(n)))];
%Y A359331 Cf. A002113, A003415, A018252, A190116.
%K A359331 nonn,base
%O A359331 1,2
%A A359331 _Marius A. Burtea_, Jan 29 2023