A046701 a(1) = a(2) = a(3) = 1, a(n) = a(n - a(n-1)) + a(n-1 - a(n-3)) (n > 3).

1, 1, 1, 2, 2, 4, 3, 4, 4, 8, 5, 6, 5, 8, 7, 12, 6, 14, 6, 13, 8, 15, 8, 19, 8, 20, 6, 21, 8, 23, 8, 27, 8, 28, 6, 29, 8, 31, 8, 35, 8, 36, 6, 37, 8, 39, 8, 43, 8, 44, 6, 45, 8, 47, 8, 51, 8, 52, 6, 53, 8, 55, 8, 59, 8, 60, 6, 61, 8, 63, 8, 67, 8, 68, 6, 69, 8, 71, 8, 75, 8

Offset

1,4

References

Sequence proposed by Reg Allenby.

Links

Ray Chandler, Table of n, a(n) for n = 1..10000

Index entries for linear recurrences with constant coefficients, signature (0, 1, 0, 0, 0, 0, 0, 1, 0, -1).

Formula

For n >= 10, a(2n)-2n is 4-periodic with period [-7,-7,-5,-6] and a(2n+1) is 4-periodic with period [8,8,8,6]. - Benoit Cloitre, Jan 01 2013

Mathematica

a[n_]:=a[n]=If[n<=3, 1, a[n-a[n-1]]+a[n-1 -a[n-3]]]; Array[a, 81] (* Ray Chandler, Aug 25 2015 *)

Crossrefs

Sequence in context: A166267 A117484 A086835 * A140472 A109168 A015134

Adjacent sequences: A046698 A046699 A046700 * A046702 A046703 A046704

Keyword

nonn

Author

R. K. Guy

Status

approved