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 A197652 Numbers that are congruent to 0 or 1 mod 10. 6
 0, 1, 10, 11, 20, 21, 30, 31, 40, 41, 50, 51, 60, 61, 70, 71, 80, 81, 90, 91, 100, 101, 110, 111, 120, 121, 130, 131, 140, 141, 150, 151, 160, 161, 170, 171, 180, 181, 190, 191, 200, 201, 210, 211, 220, 221, 230, 231, 240, 241, 250, 251, 260, 261, 270, 271 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS From Wesley Ivan Hurt, Sep 26 2015: (Start) Numbers with last digit 0 or 1. Complement of (A260181 Union A262389). (End) Numbers k such that floor(k/2) = 5*floor(k/10). - Bruno Berselli, Oct 05 2017 LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 Index entries for linear recurrences with constant coefficients, signature (1,1,-1). FORMULA a(n) = Sum_{k>=0} A030308(n,k)*b(k) with b(0)=1 and b(k) = 5*2^k = A020714(k) for k>0. From Zak Seidov, Oct 20 2011: (Start) a(n) = a(n-2)+10. a(n) = 5*n-7-2*(-1)^n. (End) From Vincenzo Librandi, Jul 11 2012: (Start) G.f.: x^2*(1+9*x)/((1+x)*(1-x)^2). a(n) = a(n-1) + a(n-2) - a(n-3) for n>3. (End) MAPLE A197652:=n->5*n-7-2*(-1)^n: seq(A197652(n), n=1..100); # Wesley Ivan Hurt, Sep 26 2015 MATHEMATICA CoefficientList[Series[x*(1+9*x)/((1+x)*(1-x)^2), {x, 0, 50}], x] (* Vincenzo Librandi, Jul 11 2012 *) PROG (PARI) a(n)=n\2*10+n%2*9-9 \\ Charles R Greathouse IV, Oct 25 2011 (MAGMA) [5*n-7-2*(-1)^n: n in [1..60]]; // Vincenzo Librandi, Jul 11 2012 CROSSREFS Cf. A020714, A030308, A260181, A262389. Sequence in context: A165265 A329818 A329447 * A261909 A325483 A235202 Adjacent sequences:  A197649 A197650 A197651 * A197653 A197654 A197655 KEYWORD nonn,easy AUTHOR Philippe Deléham, Oct 16 2011 STATUS approved

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Last modified December 12 07:31 EST 2019. Contains 329948 sequences. (Running on oeis4.)