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 A248340 #20 Nov 13 2024 17:15:43
%S A248340 0,5,75,875,9375,96875,984375,9921875,99609375,998046875,9990234375,
%T A248340 99951171875,999755859375,9998779296875,99993896484375,
%U A248340 999969482421875,9999847412109375,99999237060546875,999996185302734375,9999980926513671875
%N A248340 a(n) = 10^n - 5^n.
%H A248340 G. C. Greubel, <a href="/A248340/b248340.txt">Table of n, a(n) for n = 0..995</a>
%H A248340 <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (15,-50).
%F A248340 G.f.: 5*x/((1-5*x)*(1-10*x)).
%F A248340 a(n) = 15*a(n-1) - 50*a(n-2).
%F A248340 a(n) = 5^n*(2^n-1) = A000351(n) * A000225(n) = A011557(n) - A000351(n).
%F A248340 a(n) = 5*A016164(n-1).
%F A248340 a(n) = A016164(n) - A011557(n).
%F A248340 E.g.f.: exp(10*x) - exp(5*x). - _G. C. Greubel_, Nov 13 2024
%t A248340 Table[10^n - 5^n, {n,0,30}]
%t A248340 CoefficientList[Series[5 x/((1-5 x)(1-10 x)), {x, 0, 30}], x]
%o A248340 (Magma) [10^n-5^n: n in [0..30]];
%o A248340 (Python)
%o A248340 def A248340(n): return pow(10,n) - pow(5,n)
%o A248340 print([A248340(n) for n in range(41)]) # _G. C. Greubel_, Nov 13 2024
%Y A248340 Cf. sequences of the form k^n-5^n: A005062 (k=6), A121213 (k=7), A191468 (k=8), A191466 (k=9), this sequence (k=10), A139743 (k=11).
%Y A248340 Cf. A000225, A000351, A011557, A016164.
%K A248340 nonn,easy
%O A248340 0,2
%A A248340 _Vincenzo Librandi_, Oct 05 2014