A285507 -id:A285507 - cp's OEIS frontend

A285509 a(1) = 1; a(2) = a(3) = a(4) = 2; a(n) = a(a(n-1)-1) + a(n-a(n-3)) for n > 4.

1, 2, 2, 2, 3, 4, 5, 5, 5, 5, 6, 8, 10, 10, 10, 9, 10, 10, 10, 10, 11, 13, 18, 20, 18, 15, 15, 15, 20, 20, 19, 18, 20, 20, 20, 19, 20, 20, 20, 20, 21, 23, 31, 38, 33, 28, 20, 20, 21, 30, 39, 39, 38, 30, 29, 25, 35, 40, 40, 38, 31, 33, 36, 40, 38, 40, 35, 40, 40, 40, 39, 38, 40, 40, 40, 39, 40, 40, 40, 40, 41, 43, 54, 69

Offset: 1

Altug Alkan, Apr 20 2017

Although sequence is unpredictable with its complex growth characteristic and generational structure, it has various signs of order and there are many temporary and simple patterns on it. For example, values of a(n) such that a(n) = a(n + 1) = a(n + 2) = a(n + 3) are 5, 10, 20, 40, 80, 160, 320, 640, 1280, ...

			a(5) = 3 because a(5) = a(a(4)-1) + a(5-a(2)) = a(1) + a(3) = 2.

Altug Alkan, Table of n, a(n) for n = 1..10000
Altug Alkan, Alternative scatterplot of A285509

Cf. A005185, A055748, A284523, A285507

a[1]=1; a[2]=a[3]=a[4]=2; a[n_] := a[n] = a[a[n-1]-1] + a[n-a[n-3]]; Array[a, 84] (* Giovanni Resta, Apr 21 2017 *)

a=vector(10000); a[1]=1;a[2]=a[3]=a[4]=2; for(n=5, #a, a[n]=a[a[n-1]-1]+a[n-a[n-3]]); va = vector(10000, n, a[n])

cp's OEIS Frontend

A285509 a(1) = 1; a(2) = a(3) = a(4) = 2; a(n) = a(a(n-1)-1) + a(n-a(n-3)) for n > 4.

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