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 A004448 #39 Jul 07 2021 02:16:54
%S A004448 7,6,5,4,3,2,1,0,15,14,13,12,11,10,9,8,23,22,21,20,19,18,17,16,31,30,
%T A004448 29,28,27,26,25,24,39,38,37,36,35,34,33,32,47,46,45,44,43,42,41,40,55,
%U A004448 54,53,52,51,50,49,48,63,62,61,60,59,58,57,56,71,70,69,68,67,66,65,64,79,78,77,76,75,74,73,72,87,86,85
%N A004448 Nimsum n + 7.
%C A004448 A self-inverse permutation of the natural numbers. - _Philippe Deléham_, Nov 22 2016
%D A004448 E. R. Berlekamp, J. H. Conway and R. K. Guy, Winning Ways, Academic Press, NY, 2 vols., 1982, see p. 60.
%D A004448 J. H. Conway, On Numbers and Games. Academic Press, NY, 1976, pp. 51-53.
%H A004448 Vincenzo Librandi, <a href="/A004448/b004448.txt">Table of n, a(n) for n = 0..1000</a>
%H A004448 <a href="/index/Ni#Nimsums">Index entries for sequences related to Nim-sums</a>
%H A004448 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>
%H A004448 <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,1,-1).
%F A004448 a(n) = n + (-1)^n + 2(-1)^floor(n/2) + 4(-1)^floor(n/4). - Mitchell Harris, Jan 10 2005
%F A004448 G.f.: (8*x^8-x^7-x^6-x^5-x^4-x^3-x^2-x+7) / ((x-1)^2*(x+1)*(x^2+1)*(x^4+1)). - _Colin Barker_, Jun 29 2014
%p A004448 A004448:=n->n+(-1)^n+2*(-1)^floor(n/2)+4*(-1)^floor(n/4): seq(A004448(n), n=0..100); # _Wesley Ivan Hurt_, Apr 28 2017
%t A004448 CoefficientList[Series[(8 x^8 - x^7 - x^6 - x^5 - x^4 - x^3 - x^2 - x + 7)/((x - 1)^2 (x + 1) (x^2 + 1) (x^4 + 1)), {x, 0, 100}], x] (* _Vincenzo Librandi_, Jun 30 2014 *)
%o A004448 (PARI) Vec((8*x^8-x^7-x^6-x^5-x^4-x^3-x^2-x+7)/((x-1)^2*(x+1)*(x^2+1)*(x^4+1)) + O(x^100)) \\ _Colin Barker_, Jun 29 2014
%o A004448 (Python)
%o A004448 def a(n): return n^7
%o A004448 print([a(n) for n in range(83)]) # _Michael S. Branicky_, Jul 06 2021
%K A004448 nonn,easy
%O A004448 0,1
%A A004448 _N. J. A. Sloane_
%E A004448 More terms from _Colin Barker_, Jun 29 2014