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 A245806 #22 Apr 01 2025 17:24:59
%S A245806 2,13,109,1027,10081,100243,1000729,10002187,100006561,1000019683,
%T A245806 10000059049,100000177147,1000000531441,10000001594323,
%U A245806 100000004782969,1000000014348907,10000000043046721,100000000129140163,1000000000387420489,10000000001162261467
%N A245806 a(n) = 3^n + 10^n.
%H A245806 Vincenzo Librandi, <a href="/A245806/b245806.txt">Table of n, a(n) for n = 0..1000</a>
%H A245806 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (13,-30).
%F A245806 G.f.: (2-13*x)/((1-3*x)(1-10*x)).
%F A245806 E.g.f.: e^(3*x) + e^(10*x).
%F A245806 a(n) = 13*a(n-1)-30*a(n-2) for n>1.
%F A245806 a(n) = A000244(n) + A011557(n). - _Michel Marcus_, Aug 04 2014
%t A245806 Table[(3^n + 10^n), {n, 0, 30}] (* or *) CoefficientList[Series[(2 - 13 x)/((1 - 3 x) (1 - 10 x)), {x, 0, 30}], x]
%o A245806 (Magma) [3^n+10^n: n in [0..25]];
%o A245806 (Magma) I:=[2,13]; [n le 2 select I[n] else 13*Self(n-1)-30*Self(n-2): n in [1..25]];
%o A245806 (PARI) a(n)=3^n + 10^n \\ _Charles R Greathouse IV_, Aug 26 2014
%Y A245806 Cf. 3^n+k^n: A034472 (k=1), A007689 (k=2), A008776 (k=3), A074605 (k=4), A074606 (k=5), A074607 (k=6), A074608 (k=7), A074609 (k=8), A074610 (k=9), this sequence (k=10).
%K A245806 nonn,easy
%O A245806 0,1
%A A245806 _Vincenzo Librandi_, Aug 04 2014