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A108870
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a(n) = ceiling((9*(9/4)^n - 4) / 5).
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6
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1, 4, 9, 20, 46, 103, 233, 525, 1182, 2660, 5985, 13467, 30301, 68178, 153401, 345152, 776591, 1747331, 3931496, 8845866, 19903198, 44782196, 100759940, 226709866, 510097200, 1147718700, 2582367076, 5810325920, 13073233321, 29414774973
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OFFSET
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0,2
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COMMENTS
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The old definition was "Tokuda's good set of increments for Shell sort", but that seems to be false.
Adding 0, -1, -1, -1, ... to the terms gives A361506. For another version see A361507.
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REFERENCES
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N. Tokuda, An Improved Shellsort, IFIP Transactions, A-12 (1992) 449-457.
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LINKS
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Marcin Ciura, Best Increments for the Average Case of Shellsort, 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.
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MATHEMATICA
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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