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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, 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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified June 25 12:00 EDT 2019. Contains 324352 sequences. (Running on oeis4.)