%I #30 Oct 13 2022 13:53:42
%S 0,0,1,1,1,2,3,3,4,4,4,5,6,6,7,7,7,8,9,9,10,10,10,11,12,12,13,13,13,
%T 14,15,15,16,16,16,17,18,18,19,19,19,20,21,21,22,22,22,23,24,24,25,25,
%U 25,26,27,27,28,28,28,29,30,30,31,31,31,32,33,33,34,34,34,35,36,36,37,37,37,38,39,39,40,40,40,41,42,42,43,43,43,44
%N A sequence based on the period 6 sequence A151899.
%C a(k-1) + 2 =: v2(k), k >= 1, is used to obtain for 2^(v2(k))*V_{-k}(2) as well as 2^(v2(k))*V_{-k}(5) integer coordinates in the quadratic number field Q(sqrt(3)), where V_{-k}(j), j = 0..5, are the vertices of a k-family of regular hexagons H_{-k} whose centers O_{-k} form part of a discrete spiral. See the linked paper, Lemma 6, eqs. (47) and (48), and the Table 19. - _Wolfdieter Lang_, Mar 30 2018
%H Wolfdieter Lang, <a href="/A300068/a300068_1.pdf">On a Conformal Mapping of Regular Hexagons and the Spiral of its Centers</a>
%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,0,1,-1).
%F a(n) = A151899(n) + 3*floor(n/6), n >= 0.
%F a(n) = A300076(n+1) - 1.
%F G.f.: x^2*(1 + x^3 + x^4)/((1 - x^6)*(1 - x)) = G(x) + 3*x^6/((1-x)*(1-x^6)), with the g.f. G(x) of A151899.
%o (PARI) a151899(n) = [0, 0, 1, 1, 1, 2][n%6+1]
%o a(n) = a151899(n) + 3*floor(n/6) \\ _Felix Fröhlich_, Mar 30 2018
%Y Cf. A174257, A300068, A300076, A151899.
%K nonn,easy
%O 0,6
%A _Wolfdieter Lang_, Mar 05 2018