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A080867
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Dorey's period-90 sequence (periodic from a(1)=1 onward).
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3
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0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 3, 7, 5, 1, 4, 9, 9, 8, 7, 2, 5, 6, 3, 0, 1, 5, 1, 6, 9, 7, 9, 6, 5, 6, 1, 7, 6, 7, 3, 3, 6, 3, 9, 5, 1, 8, 5, 6, 9, 4, 3, 2, 7, 0, 1, 9, 3, 5, 1, 0, 1, 1, 2, 9, 2, 1, 3, 8, 3, 1, 4, 7, 7, 4, 1, 5, 6, 5, 1, 6, 1, 7, 1, 8, 1, 9, 1, 0, 1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 3, 7, 5, 1, 4, 9, 9, 8, 7, 2, 5, 6, 3, 0, 1, 5, 1, 6
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OFFSET
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0,3
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LINKS
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Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1).
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FORMULA
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a(n<12) = n mod 10, a(n>11) = a(n-1)+a(i+1) mod 10, where i (< n-1) is the first position to left of n-1 where a(n-1) occurs.
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MAPLE
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A080867 := proc(n) option remember; local i, u; if(n < 12) then RETURN(n mod 10); else u := A080867(n-1); for i from n-2 by -1 to 0 do if(A080867(i) = u) then RETURN((A080867(i+1)+u) mod 10); fi; od; fi; RETURN(-1); end;
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CROSSREFS
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KEYWORD
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nonn,base,easy
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AUTHOR
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Laurent Dorey (laurentdorey(AT)wanadoo.fr) and Antti Karttunen, Feb 21 2003
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STATUS
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approved
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