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 A057493 #16 Feb 23 2017 21:35:15 %S A057493 1,3,7,9,21,27,49,63,81,111,147,171,189,203,243,333,343,441,513,567, %T A057493 609,729,777,999,1029,1143,1197,1323,1421,1539,1701,1791,1827,2187, %U A057493 2331,2401,2943,2997,3087,3249,3429,3591,3969,4107,4263,4617,5103,5373 %N A057493 Numbers n such that n | 11^n + 10^n. %C A057493 From _Robert Israel_, Feb 23 2017: (Start) %C A057493 Contains A003594. %C A057493 Every term other than 1 is divisible by 3 or 7. %C A057493 If m and n are in the sequence, then so is m*n. (End) %H A057493 Robert Israel, <a href="/A057493/b057493.txt">Table of n, a(n) for n = 1..5305</a> (first 580 terms from Vincenzo Librandi) %p A057493 select(t -> (10 &^ t + 11 &^ t mod t = 0), [seq(i,i=1..10000,2)]); # _Robert Israel_, Feb 23 2017 %t A057493 Select[ Range[ 10000 ], Mod[ PowerMod[ 11, #, # ] + PowerMod[ 10, #, # ], # ] == 0 & ] %o A057493 (PARI) is(n)=Mod(11,n)^n+Mod(10,n)^n==0 \\ _Charles R Greathouse IV_, Feb 23 2017 %Y A057493 Cf. A003594. %K A057493 nonn %O A057493 1,2 %A A057493 _Robert G. Wilson v_, Sep 20 2000