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 A081890 #17 Sep 12 2024 19:59:15
%S A081890 1,3,7,33,643,11073,151867,1816713,19996963,208630833,2099398027,
%T A081890 20597485593,198424412083,1885822419393,17740469253787,
%U A081890 165580566245673,1535948935336003,14178113530908753,130361707324735147,1194785495130736953,10921581632007328723,99616564791408530913
%N A081890 a(n) = 9^n - 8^n - 7^n - 6^n + 3*5^n.
%C A081890 Binomial transform of A081687.
%H A081890 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (35,-485,3325,-11274,15120).
%F A081890 G.f.: -(4182*x^4-2082*x^3+387*x^2-32*x+1)/((5*x-1)*(6*x-1)*(7*x-1)*(8*x-1)*(9*x-1)). [_Colin Barker_, Aug 12 2012]
%F A081890 From _Elmo R. Oliveira_, Sep 12 2024: (Start)
%F A081890 E.g.f.: exp(5*x)*(exp(4*x) - exp(3*x) - exp(2*x) - exp(x) + 3).
%F A081890 a(n) = 35*a(n-1) - 485*a(n-2) + 3325*a(n-3) - 11274*a(n-4) + 15120*a(n-5) for n > 4. (End)
%t A081890 LinearRecurrence[{35,-485,3325,-11274,15120},{1,3,7,33,643},30] (* _Harvey P. Dale_, Jun 26 2017 *)
%Y A081890 Cf. A081687, A081691.
%K A081890 easy,nonn
%O A081890 0,2
%A A081890 _Paul Barry_, Mar 30 2003
%E A081890 a(19)-a(21) from _Elmo R. Oliveira_, Sep 12 2024