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 A080867 Dorey's period-90 sequence (periodic from a(1)=1 onward). 3
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS FORMULA 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. MAPLE 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; CROSSREFS Cf. A080868. Sequence in context: A007954 A079475 A081286 * A095187 A218978 A309589 Adjacent sequences:  A080864 A080865 A080866 * A080868 A080869 A080870 KEYWORD nonn,base AUTHOR Laurent Dorey (laurentdorey(AT)wanadoo.fr) & Antti Karttunen Feb 21 2003. STATUS approved

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Last modified February 24 01:16 EST 2020. Contains 332195 sequences. (Running on oeis4.)