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

Offset

0,3

Links

Ray Chandler, Table of n, a(n) for n = 0..1000

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: A007954 A079475 A081286 * A095187 A218978 A309589

Adjacent sequences: A080864 A080865 A080866 * A080868 A080869 A080870

Keyword

nonn,base,easy

Author

Laurent Dorey (laurentdorey(AT)wanadoo.fr) and Antti Karttunen, Feb 21 2003

Status

approved