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 A239433 #8 Jan 24 2024 13:54:57 %S A239433 4,5,6,7,8,9,10,12,13,14,15,16,18,19,20,21,22,24,25,26,27,28,30,31,32, %T A239433 33,34,36,38,39,40,41,42,43,44,45,46,48,49,50,51,52,54,55,56,58,59,60, %U A239433 61,62,63,64,66,68,69,70,71,72,73,74,75,76,77,78,80,81 %N A239433 Numbers m with at least one integer solution for x' = m, where x' is the arithmetic derivative of x (cf. A003415). %C A239433 A099302(a(n)) > 0. %H A239433 Reinhard Zumkeller, <a href="/A239433/b239433.txt">Table of n, a(n) for n = 1..1000</a> %o A239433 (Haskell) %o A239433 a239433 n = a239433_list !! (n-1) %o A239433 a239433_list = filter %o A239433 (\z -> any (== z) $ map a003415 $ takeWhile (<= a002620 z) a013929_list) [2..] %Y A239433 Cf. A002620, A098700 (complement), A369251 (subsequence). %K A239433 nonn %O A239433 1,1 %A A239433 _Reinhard Zumkeller_, Mar 18 2014