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%I #34 Dec 03 2023 18:38:25
%S 1,4,10,23,57,132,301,701,1750
%N Optimal (best known) sequence of increments for shell sort algorithm.
%C Values were found empirically. Better than A033622, A036562, A036564, A036569, and A055875.
%H Marcin Ciura, <a href="https://doi.org/10.1007/3-540-44669-9_12">Best Increments for the Average Case of Shellsort</a>, in R. Freivalds, (ed.), Fundamentals of Computation Theory: 13th International Symposium, FCT 2001, Riga, Latvia, August 2001, Lecture Notes in Computer Science, vol. 2138, Springer, pp. 106-117.
%e a(0) = 1 performs a single pass of Shellsort with a gap size of 1 (which is identical to the Insertion Sort algorithm).
%e a(1) = 4 performs a single pass of Shellsort with a gap size of 4 (exchanging elements 4 positions apart if they are out of order).
%Y Cf. A033622, A036562, A036564, A036569, A055875.
%K hard,nonn
%O 0,2
%A Gunther Piez (gpiez(AT)web.de), Feb 24 2005
%E a(8) = 1750 from _Roman Dovgopol_, May 08 2011
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