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 A045592 #15 Aug 10 2021 04:53:38 %S A045592 1,11,121,253,737,1331,2783,5819,8107,14641,16951,30613,49379,64009, %T A045592 89177,116897,133837,161051,186461,336743,389873,543169,640343,704099, %U A045592 980947,1135717,1285867,1292071,1472207,1771561,2051071,2688631 %N A045592 Numbers k that divide 7^k + 4^k. %t A045592 Select[Range[269*10^4],Mod[PowerMod[7,#,#]+PowerMod[4,#,#],#]==0&] (* _Harvey P. Dale_, Jun 25 2021 *) %Y A045592 Cf. A074613. %K A045592 nonn %O A045592 1,2 %A A045592 _David W. Wilson_