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A178770 a(0) = a(1) = a(2) = a(3) = a(4) = 1, thereafter a(n) = a(a(n-1)) + a(n-a(n-3)). 2
1, 1, 1, 1, 1, 2, 3, 4, 4, 4, 4, 5, 6, 7, 8, 8, 8, 8, 8, 9, 10, 11, 12, 13, 14, 15, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 26, 26, 26, 27, 28, 29, 30, 30, 30, 30, 31, 31, 31, 31, 31, 32, 32, 32, 32, 32, 32, 32, 33, 34, 35, 36, 37, 38, 39, 40 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,6

COMMENTS

The sequence has many plateaus where numbers repeat three times or more. 16 appears 6 times in a row. The long start up vector produces this phase locking / staircase behavior which is probably due to feedback effects.

LINKS

Muniru A Asiru, Table of n, a(n) for n = 0..10000

MAPLE

a:= proc(n) option remember: if n<5 then 1 else procname(procname(n-1))+procname(n-procname(n-3)) fi end: seq(a(n), n=0..80); # Muniru A Asiru, Jun 05 2018

MATHEMATICA

a[0] = 1; a[1] = 1; a[2] = 1; a[3] = 1;

a[4] = 1; (*a[4]=3; a[5]=2; a[6]=3*);

a[n_Integer] := a[n] = a[a[n - 1]] + a[n - a[-3 + n]]

b = Table[a[n], {n, 0, 200}]

PROG

(GAP) a:=[1, 1, 1, 1];; for n in [5..80] do a[n]:=a[a[n-1]]+a[n-a[n-3]]; od;

a:=Concatenation([1], a); # Muniru A Asiru, Jun 05 2018

CROSSREFS

Cf. A004001.

Sequence in context: A194167 A140427 A194816 * A072229 A120509 A029106

Adjacent sequences:  A178767 A178768 A178769 * A178771 A178772 A178773

KEYWORD

nonn,easy

AUTHOR

Roger L. Bagula, Jun 11 2010

STATUS

approved

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Last modified April 6 11:02 EDT 2020. Contains 333273 sequences. (Running on oeis4.)