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 A024090 #17 Jul 08 2025 17:27:30
%S A024090 1,7,60,503,4080,32743,262108,2097103,16777152,134217647,1073741724,
%T A024090 8589934471,68719476592,549755813719,4398046510908,35184372088607,
%U A024090 281474976710400,2251799813684959,18014398509481660
%N A024090 8^n-n^2.
%H A024090 Vincenzo Librandi, <a href="/A024090/b024090.txt">Table of n, a(n) for n = 0..400</a>
%H A024090 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (11,-27,25,-8).
%F A024090 G.f.: (1-4*x+10*x^2+7*x^3)/((1-8*x)*(1-x)^3). - _Vincenzo Librandi_, Oct 06 2014
%F A024090 a(n) = 11*a(n-1) -27*a(n-2) +25*a(n-3) -8*a(n-4) for n>3. - _Vincenzo Librandi_, Oct 06 2014
%F A024090 a(n) = A001018(n) - A000290(n). - _Michel Marcus_, Oct 06 2014
%t A024090 Table[8^n - n^2, {n, 0, 25}] (* or *) CoefficientList[Series[(1 - 4 x + 10 x^2 + 7 x^3)/((1 - 8 x) (1 - x)^3), {x, 0, 30}], x] (* _Vincenzo Librandi_, Oct 06 2014 *)
%t A024090 LinearRecurrence[{11,-27,25,-8},{1,7,60,503},30] (* _Harvey P. Dale_, Feb 13 2023 *)
%o A024090 (Magma) [8^n-n^2: n in [0..20]]; // _Vincenzo Librandi_, Jul 05 2011
%Y A024090 Cf. similar sequences listed in A024025.
%K A024090 nonn,easy
%O A024090 0,2
%A A024090 _N. J. A. Sloane_