A081595 Let n = 10x + y where 0 <= y <= 9, x >= 0. Then a(n) = 4x+y.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 28, 29, 30, 31, 32, 33, 34, 35

Offset

0,3

Links

Vincenzo Librandi, Table of n, a(n) for n = 0..2000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,0,0,0,1,-1).

Formula

G.f.: -x*(5*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

a(n) = n - 6*floor(n/10). [Bruno Berselli, Jun 24 2014]

Mathematica

CoefficientList[Series[-x (5 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 *)
LinearRecurrence[{1, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1}, {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 4}, 80] (* Harvey P. Dale, Sep 17 2023 *)

Prog

(PARI) my(n, x, y); vector(200, n, y=(n-1)%10; x=(n-1-y)\10; 4*x+y) \\ Colin Barker, Jun 24 2014
(Magma) k:=4; [n-(10-k)*Floor(n/10): n in [0..100]]; // Bruno Berselli, Jun 24 2014

Crossrefs

Cf. A081502. Different from A028899.

Sequence in context: A122666 A114288 A028899 * A122644 A209928 A363372

Adjacent sequences: A081592 A081593 A081594 * A081596 A081597 A081598

Keyword

nonn

Author

N. J. A. Sloane, Apr 22 2003

Status

approved