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 A211823 #11 Aug 27 2020 16:34:33 %S A211823 0,2,4,8,12,14,18,20,22,30,34,40,42,44,48,54,58,60,64,68,70,78,82,84, %T A211823 90,92,98,102,104,110,112,118,124,128,130,142,144,152,154,158,162,170, %U A211823 172,174,180,184,188,194,198,200,208,222,224,228,230,232,238,240,242 %N A211823 Numbers k such that 9*k+1 are numbers with all divisors with additive digital root = 1. %C A211823 Numbers of form 9*k+1 with all divisors with digital root = 1 is in A211821. %C A211823 Supersequence of A024906 (numbers n such that 9*n+1 is prime). %H A211823 Harvey P. Dale, <a href="/A211823/b211823.txt">Table of n, a(n) for n = 1..1000</a> %e A211823 Number k = 40 is in sequence because number 9*40 + 1 = 361 is number with all divisors (1, 19, 361) with additive digital root = 1. %t A211823 adrQ[n_]:=NestWhile[Total[IntegerDigits[#]]&,n,#>9&]==1; Select[Range[ 0,250],AllTrue[Divisors[9#+1],adrQ]&] (* Requires Mathematica version 10 or later *) (* _Harvey P. Dale_, Aug 27 2020 *) %Y A211823 Cf. A211821, A024906, A061237, A017173, A211822 %K A211823 nonn,base %O A211823 1,2 %A A211823 _Jaroslav Krizek_, Apr 26 2012 %E A211823 Corrected (230 inserted) by _Harvey P. Dale_, Aug 27 2020