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 A001580 #32 Apr 23 2023 12:23:28
%S A001580 1,3,8,17,32,57,100,177,320,593,1124,2169,4240,8361,16580,32993,65792,
%T A001580 131361,262468,524649,1048976,2097593,4194788,8389137,16777792,
%U A001580 33555057,67109540,134218457,268436240
%N A001580 a(n) = 2^n + n^2.
%D A001580 G. Everest, A. van der Poorten, I. Shparlinski and T. Ward, Recurrence Sequences, Amer. Math. Soc., 2003; see esp. p. 255.
%D A001580 P. R. Halmos, Problems for Mathematicians Young and Old. Math. Assoc. America, 1991, p. 179.
%H A001580 Vincenzo Librandi, <a href="/A001580/b001580.txt">Table of n, a(n) for n = 0..1000</a>
%H A001580 <a href="/index/Rec#order_04">Index entries for linear recurrences with constant coefficients</a>, signature (5,-9,7,-2).
%F A001580 G.f.: (2*x-2*x^2+3*x^3-1)/(1-x)^3/(-1+2*x). a(n) = 2*A000217(n+1)+A000079(n) -3*A000027(n+1)+1. - _R. J. Mathar_, Nov 16 2007
%t A001580 f[n_]:=n^2+2^n; Table[f[n],{n,0,5!}] (* _Vladimir Joseph Stephan Orlovsky_, Dec 05 2009 *)
%t A001580 LinearRecurrence[{5,-9,7,-2},{1,3,8,17},30] (* _Harvey P. Dale_, Jan 05 2020 *)
%o A001580 (Magma) [2^n+n^2: n in [0..35]]; // _Vincenzo Librandi_, Jun 07 2011
%o A001580 (PARI) a(n)=2^n+n^2 \\ _Charles R Greathouse IV_, Apr 17 2012
%o A001580 (Maxima) A001580(n):=2^n+n^2$ makelist(A001580(n),n,0,20); /* _Martin Ettl_, Dec 18 2012 */
%o A001580 (Python)
%o A001580 def A001580(n): return (1<<n)+n**2 # _Chai Wah Wu_, Apr 23 2023
%K A001580 nonn,easy
%O A001580 0,2
%A A001580 _N. J. A. Sloane_