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%I #15 Jan 08 2024 10:55:10
%S 1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,
%T 8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,
%U 6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,1,2,3,4,5,6
%N Periodic sequence: Repeat 1, 2, 3, 4, 5, 6, 7, 8, 9.
%C Interleaving of A131669 and A131669 without first five terms.
%C Continued fraction expansion of (684125+sqrt(635918528029))/1033802.
%C Decimal expansion of 13717421/111111111.
%C a(n) = A010888(n+1) = A010878(n)+1 = A117230(n+2)-1.
%C a(n) = A064806(n+1)-n-1.
%C Essentially first differences of A037123.
%H <a href="/index/Rec#order_09">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,1).
%F a(n) = (n mod 9)+1.
%F a(n) = a(n-9) for n > 8; 1; a(n) = n+1 for n <= 8.
%F G.f.: (1+2*x+3*x^2+4*x^3+5*x^4+6*x^5+7*x^6+8*x^7+9*x^8)/(1-x^9). [corrected by _Georg Fischer_, May 11 2019]
%t PadRight[{},120,Range[9]] (* _Paolo Xausa_, Jan 08 2024 *)
%o (Magma) &cat[ [1, 2, 3, 4, 5, 6, 7, 8, 9]: k in [1..12] ];
%Y Cf. A131669 (odd digits followed by positive even digits), A010888 (digital root of n), A010878 (n mod 9), A117230 (1 followed by (repeat 2, 3, 4, 5, 6, 7, 8, 9, 10), offset 1), A064806 (n + digital root of n), A037123, A177270 (decimal expansion of (684125+sqrt(635918528029))/1033802).
%K cofr,easy,nonn
%O 0,2
%A _Klaus Brockhaus_, May 07 2010
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