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 A074502 #19 Jan 26 2023 10:05:32
%S A074502 3,9,41,225,1313,7809,46721,280065,1679873,10078209,60467201,
%T A074502 362799105,2176786433,13060702209,78364180481,470185017345,
%U A074502 2821109972993,16926659575809,101559956930561,609359740534785,3656158441111553
%N A074502 a(n) = 1^n + 2^n + 6^n.
%C A074502 From _Jonathan Vos Post_, Apr 16 2005: (Start)
%C A074502 Primes in this sequence include: a(2) = 41, a(10) = 60467201, a(18) = 101559956930561, a(34) = 286511799958070449017978881, a(58) = 1357602166130257152481187563448636039086735361.
%C A074502 Semiprimes in this sequence include: a(1) = 9 = 3^2, a(4) = 1313 = 13 * 101, a(6) = 46721 = 19 * 2459, a(8) = 1679873 = 13 * 129221, a(12) = 2176786433 = 19 * 114567707, a(13) = 13060702209 = 3 * 4353567403, a(28) = 6140942214465083932673 = 13 * 472380170343467994821, a(29) = 36845653286789429854209 = 3 * 12281884428929809951403, a(72) = 106387358923716524807713475752456398462534338499504504833 = 59670762632990981 * 1782905969847563299479030657520813855693. (End)
%H A074502 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-20,12).
%F A074502 G.f.: 1/(1-x)+1/(1-2*x)+1/(1-6*x). E.g.f.: e^x+e^(2*x)+e^(6*x). [_Mohammad K. Azarian_, Dec 26 2008]
%F A074502 a(n) = 8*a(n-1) - 12*a(n-2) + 5, n> 1. [_Gary Detlefs_, Jun 21 2010]
%t A074502 Table[1^n + 2^n + 6^n, {n, 0, 20}]
%t A074502 LinearRecurrence[{9,-20,12},{3,9,41},30] (* _Harvey P. Dale_, Aug 15 2017 *)
%Y A074502 Cf. A001550, A001576, A034513, A001579, A074501 - A074580.
%K A074502 easy,nonn
%O A074502 0,1
%A A074502 _Robert G. Wilson v_, Aug 23 2002