A080867 - OEIS

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A080867

Dorey's period-90 sequence (periodic from a(1)=1 onward).

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; internal format)

	OFFSET	`0,3`
	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 A169931 A141022` `Adjacent sequences: A080864 A080865 A080866 * A080868 A080869 A080870`
	KEYWORD	`nonn,base`
	AUTHOR	`Laurent Dorey (laurentdorey(AT)wanadoo.fr) & Antti Karttunen (my_firstname.my_surname(AT)iki.fi) Feb 21 2003.`

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Last modified February 17 00:09 EST 2012. Contains 205978 sequences.