A287155 a(1) = 1 by convention. a(2) = a(3) = a(4) = 2; a(n) = a(a(n-1)) + a(n-a(n-1)) for n > 4.

1, 2, 2, 2, 4, 4, 4, 4, 6, 6, 8, 6, 8, 8, 8, 8, 10, 10, 12, 10, 14, 12, 14, 14, 16, 14, 16, 14, 16, 16, 16, 16, 18, 18, 20, 18, 22, 20, 22, 22, 24, 24, 26, 24, 28, 24, 28, 24, 30, 26, 30, 28, 30, 30, 32, 30, 32, 30, 32, 30, 32, 32, 32, 32, 34, 34, 36, 34, 38, 36, 38, 38, 40, 40

Offset

1,2

Links

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

Altug Alkan, Line graph of a(n)-n/2

Mathematica

a[1] = 1; a[2] = a[3] = a[4] = 2; a[n_] := a[n] = a[a[n - 1]] + a[n - a[n - 1]]; Array[a, 74] (* Michael De Vlieger, May 20 2017 *)

Prog

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

Crossrefs

Cf. A004001.

Sequence in context: A317841 A007614 A289256 * A287654 A355911 A369207

Adjacent sequences: A287152 A287153 A287154 * A287156 A287157 A287158

Keyword

nonn

Author

Altug Alkan, May 20 2017

Status

approved