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%I #18 Feb 03 2023 01:40:38
%S 0,2,4,6,8,0,2,4,6,8,10,12,14,16,18,10,12,14,16,18,20,22,24,26,28,20,
%T 22,24,26,28,30,32,34,36,38,30,32,34,36,38,40,42,44,46,48,40,42,44,46,
%U 48,50,52,54,56,58,50,52,54,56,58,60,62,64,66,68,60,62,64,66,68,70,72,74,76,78
%N a(n) = 2+n in the arithmetic defined in A169918.
%C Equivalently, apply to the last (decimal) digit of n the operation d->((d*2) mod 10), i.e., multiply the last digit by 2 and take this modulo 10; keep all other digits the same. - _M. F. Hasler_, Mar 25 2015
%H <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 For n > 9, a(n) = a(n-10) + 10. For n < 10, a(n) = (2*n mod 10). - _M. F. Hasler_, Mar 25 2015
%F From _Chai Wah Wu_, Feb 02 2023: (Start)
%F a(n) = a(n-1) + a(n-10) - a(n-11) for n > 10.
%F G.f.: 2*x*(x^9 + x^8 + x^7 + x^6 + x^5 - 4*x^4 + x^3 + x^2 + x + 1)/(x^11 - x^10 - x + 1). (End)
%o (PARI) A169933(n)=n-n%10+(n*2)%10 \\ _M. F. Hasler_, Mar 25 2015
%o (Magma) [n - n mod 10 + 2*n mod 10: n in [0..70]]; // _Vincenzo Librandi_, Mar 26 2015
%Y Cf. A169931 - A169935.
%K nonn,base
%O 0,2
%A _David Applegate_, _Marc LeBrun_ and _N. J. A. Sloane_, Jul 20 2010
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