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%I #19 Aug 09 2022 23:17:10
%S 1,4,6,9,11,13,16,18,21,23,25,28,30,33,35,37,40,42,45,47,49,52,54,57,
%T 59,61,64,66,69,71,73,76,78,81,83,85,88,90,93,95,97,100,102,105,107,
%U 109,112,114,117,119,121,124,126,129,131,133,136,138,141,143,145,148
%N Numbers that are congruent to {1, 4, 6, 9, 11} mod 12. The ebony keys on a piano, starting with A0 = the 0th key.
%C A piano sequence since if a(n) < 88 then A059620(a(n)) = 1.
%H Colin Barker, <a href="/A060106/b060106.txt">Table of n, a(n) for n = 1..1000</a>
%H <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,1,-1).
%F a(n) = a(n-5) + 12.
%F a(n) = A081032(n) - 1 for 1 <= n <= 36. - _Jianing Song_, Oct 14 2019
%F From _Colin Barker_, Oct 14 2019: (Start)
%F G.f.: x*(1 + 3*x + 2*x^2 + 3*x^3 + 2*x^4 + x^5) / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4)).
%F a(n) = a(n-1) + a(n-5) - a(n-6) for n > 6.
%F (End)
%o (PARI) Vec(x*(1 + 3*x + 2*x^2 + 3*x^3 + 2*x^4 + x^5) / ((1 - x)^2*(1 + x + x^2 + x^3 + x^4)) + O(x^60)) \\ _Colin Barker_, Oct 14 2019
%Y Cf. A059620, A081032. Complement of A060107.
%K easy,nonn
%O 1,2
%A _Henry Bottomley_, Feb 27 2001
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