A140724 Period 10: 1, 5, 9, 7, 7, 9, 5, 1, 3, 3 repeated.

1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7, 9, 5, 1, 3, 3, 1, 5, 9, 7, 7

Offset

0,2

Comments

The last digit of A108981(n).

Also the continued fraction of (290003+sqrt(240183699293))/652402.

Also the decimal expansion of 13073/81819.

The period contains each of the 5 odd digits twice.

Links

Table of n, a(n) for n=0..104.

Index entries for linear recurrences with constant coefficients, signature (2,-2,2,-2,1).

Formula

a(n)+a(n+5) = 10 = A010692(n).

a(n) = a(n+10) .

a(10*k+9+i) = a(10*k+18-i) (palindromic).

a(n) = 2*a(n-1)-2*a(n-2)+2*a(n-3)-2*a(n-4)+a(n-5). G.f.: -(1+3*x+x^2-3*x^3+3*x^4)/ ((x-1) * (x^4-x^3+x^2-x+1)).

Mathematica

PadRight[{}, 120, {1, 5, 9, 7, 7, 9, 5, 1, 3, 3}] (* Harvey P. Dale, Apr 23 2020 *)

Prog

(PARI) 13073/81819. \\ Charles R Greathouse IV, Jul 21 2015

Crossrefs

Sequence in context: A195285 A348682 A200597 * A086055 A219734 A077125

Adjacent sequences: A140721 A140722 A140723 * A140725 A140726 A140727

Keyword

nonn,easy

Author

Paul Curtz, Jul 12 2008

Extensions

Edited by R. J. Mathar, Sep 07 2009

Status

approved