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 A045588 #19 Oct 23 2021 10:06:39 %S A045588 1,2,3,6,9,10,18,21,27,30,50,54,63,81,90,147,150,162,171,189,243,250, %T A045588 270,333,438,441,450,486,513,567,729,750,810,903,999,1029,1197,1250, %U A045588 1314,1323,1350,1458,1539,1701,2187,2190,2250,2331,2430,2709,2997,3087 %N A045588 Numbers k that divide 9^k + 3^k. %H A045588 Amiram Eldar, <a href="/A045588/b045588.txt">Table of n, a(n) for n = 1..10000</a> %t A045588 Select[Range[3100],Divisible[9^#+3^#,#]&] (* _Harvey P. Dale_, Aug 13 2015 *) %t A045588 Select[Range[300], Divisible[PowerMod[9, #, #] + PowerMod[3, #, #], #] &] (* _Amiram Eldar_, Oct 23 2021 *) %Y A045588 Cf. A074610. %K A045588 nonn %O A045588 1,2 %A A045588 _David W. Wilson_