%I #28 Sep 08 2023 07:33:13
%S 0,9,18,9,36,45,18,63,72,9,90,99,36,117,126,45,144,153,18,171,180,63,
%T 198,207,72,225,234,27,252,261,90,279,288,99,306,315,36,333,342,117,
%U 360,369,126,387,396,45,414,423,144,441,450,153,468,477,54,495,504
%N a(n) = lcm(n, 9).
%H Amiram Eldar, <a href="/A109050/b109050.txt">Table of n, a(n) for n = 0..10000</a>
%H <a href="/index/Rec#order_18">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,2,0,0,0,0,0,0,0, 0,-1).
%H <a href="/index/Lc#lcm">Index entries for sequences related to lcm's</a>.
%F a(n) = n*9/gcd(n, 9).
%F a(n) = 9*n/A109012(n) = 9*A106610(n). - _R. J. Mathar_, Apr 18 2011
%F Sum_{k=1..n} a(k) ~ (61/18) * n^2. - _Amiram Eldar_, Nov 26 2022
%F Sum_{n>=1} (-1)^(n+1)/a(n) = 7*log(2)/27. - _Amiram Eldar_, Sep 08 2023
%t LCM[9,Range[0,60]] (* _Harvey P. Dale_, Aug 21 2021 *)
%o (Sage) [lcm(n,9)for n in range(0, 57)] # _Zerinvary Lajos_, Jun 09 2009
%o (Magma) [Lcm(n,9): n in [0..100]]; // _Vincenzo Librandi_, Apr 18 2011
%Y Cf. A106610, A109012, A109042.
%K nonn,easy
%O 0,2
%A _Mitch Harris_, Jun 18 2005