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%I #11 Dec 23 2024 14:53:43
%S 1,2,3,4,5,9,7,8,15,10,11,21,13,14,27,16,17,33,19,20,39,22,23,45,25,
%T 26,51,28,29,57,31,32,63,34,35,69,37,38,75,40,41,81,43,44,87,46,47,93,
%U 49,50,99,52,53,105,55,56,111,58,59,117,61,62,123,64,65,129,67,68,135,70,71,141,73
%N Lexicographically earliest injective sequence of positive integers such that the sum of 6 consecutive terms is always divisible by 6.
%H E. Angelini, <a href="https://web.archive.org/web/*/http://list.seqfan.eu/oldermail/seqfan/2013-March/010956.html">k-chunks sum and division by k</a>, post to the SeqFan list, Mar 22 2013
%F a(n) = 2 a(n-3) - a(n-6).
%F G.f. (1 + 2*x + 3*x^2 + 2*x^3 + x^4 + 3*x^5)/((1 - x)*(1 + x + x^2))^2.
%Y Cf. A222256, A222258 - A222261.
%K nonn
%O 0,2
%A _Eric Angelini_ and _M. F. Hasler_, Mar 23 2013