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 A074507 #29 Mar 02 2022 18:04:41
%S A074507 3,9,35,153,707,3369,16355,80313,397187,1972809,9824675,49005273,
%T A074507 244672067,1222297449,6108298595,30531927033,152630937347,
%U A074507 763068593289,3815084686115,19074648589593,95370918425027,476847618556329
%N A074507 a(n) = 1^n + 3^n + 5^n.
%H A074507 Harvey P. Dale, <a href="/A074507/b074507.txt">Table of n, a(n) for n = 0..1000</a>
%H A074507 T. A. Gulliver, <a href="http://www.m-hikari.com/imf-2010/61-64-2010/gulliverIMF61-64-2010.pdf">Divisibility of sums of powers of odd integers</a>, Int. Math. For. 5 (2010) 3059-3066, eq. (6).
%H A074507 D. Suprijanto, I. W. Suwarno, <a href="http://dx.doi.org/10.12988/ams.2014.4139">Observation on Sums of Powers of Integers Divisible by 3k-1</a>, Applied Mathematical Sciences, Vol. 8, 2014, no. 45, 2211 - 2217.
%H A074507 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (9,-23,15).
%F A074507 a(n) = 8*a(n-1) - 15*a(n-2) + 8.
%F A074507 G.f.: 1/(1-x)+1/(1-3*x)+1/(1-5*x). E.g.f.: e^x+e^(3*x)+e^(5*x). [_Mohammad K. Azarian_, Dec 26 2008]
%t A074507 Table[1^n + 3^n + 5^n, {n, 0, 22}]
%t A074507 LinearRecurrence[{9,-23,15},{3,9,35},30] (* _Harvey P. Dale_, Mar 02 2022 *)
%o A074507 (PARI) a(n) = 1 + 3^n + 5^n; \\ _Michel Marcus_, Aug 07 2017
%Y A074507 Cf. A001550, A001576, A034513, A001579, A074501-A074580.
%K A074507 easy,nonn
%O A074507 0,1
%A A074507 _Robert G. Wilson v_, Aug 23 2002