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 A081597 #24 Feb 26 2025 10:58:15
%S A081597 0,1,2,3,4,5,6,7,8,9,6,7,8,9,10,11,12,13,14,15,12,13,14,15,16,17,18,
%T A081597 19,20,21,18,19,20,21,22,23,24,25,26,27,24,25,26,27,28,29,30,31,32,33,
%U A081597 30,31,32,33,34,35,36,37,38,39,36,37,38,39,40,41,42,43,44,45,42,43,44,45,46,47
%N A081597 Let n = 10*x + y where 0 <= y <= 9, x >= 0. Then a(n) = 6*x + y.
%H A081597 Vincenzo Librandi, <a href="/A081597/b081597.txt">Table of n, a(n) for n = 0..2000</a>
%H A081597 <a href="/index/Rec#order_11">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,0,0,0,0,1,-1).
%F A081597 G.f.: -x*(3*x^9 -x^8 -x^7 -x^6 -x^5 -x^4 -x^3 -x^2 -x -1) / ((x -1)^2*(x +1)*(x^4 -x^3 +x^2 -x +1)*(x^4 +x^3 +x^2 +x +1)). - _Colin Barker_, Jun 24 2014
%F A081597 a(n) = n - 4*floor(n/10). [_Bruno Berselli_, Jun 24 2014]
%F A081597 a(n) = a(n-1) + a(n-10) - a(n-11) for n > 10. - _Chai Wah Wu_, Apr 25 2017
%p A081597 A081597:=n->n-4*floor(n/10): seq(A081597(n), n=0..150); # _Wesley Ivan Hurt_, Apr 25 2017
%t A081597 CoefficientList[Series[-x (3 x^9 - x^8 - x^7 - x^6 - x^5 - x^4 - x^3 - x^2 - x - 1)/((x - 1)^2 (x + 1) (x^4 - x^3 + x^2 - x + 1) (x^4 + x^3 + x^2 + x + 1)), {x, 0, 150}], x] (* _Vincenzo Librandi_, Jun 25 2014 *)
%o A081597 (PARI) my(n, x, y); vector(200, n, y=(n-1)%10; x=(n-1-y)\10; 6*x+y) \\ _Colin Barker_, Jun 24 2014
%o A081597 (Magma) k:=6; [n-(10-k)*Floor(n/10): n in [0..10]]; // _Bruno Berselli_, Jun 24 2014
%Y A081597 Cf. A081502. Different from A028901.
%K A081597 nonn,easy
%O A081597 0,3
%A A081597 _N. J. A. Sloane_, Apr 22 2003