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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
OFFSET
0,3
LINKS
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).
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: A079475 A373102 A081286 * A095187 A218978 A309589
KEYWORD
nonn,base,easy
AUTHOR
Laurent Dorey (laurentdorey(AT)wanadoo.fr) and Antti Karttunen, Feb 21 2003
STATUS
approved