A285763 a(n) = a(a(n - 2)) + a(n - a(n - 2)), with a(1) = 1, a(2) = a(3) = a(4) = 2, a(5) = 3.

1, 2, 2, 2, 3, 4, 4, 4, 5, 6, 7, 8, 8, 8, 8, 8, 9, 10, 11, 12, 13, 14, 14, 14, 15, 16, 16, 16, 16, 16, 16, 16, 17, 18, 19, 20, 21, 22, 23, 24, 24, 24, 25, 26, 27, 28, 28, 28, 29, 30, 30, 30, 30, 30, 31, 32, 32, 32, 32, 32, 32, 32, 32, 32

Offset

1,2

Comments

The sequence a(n) is monotonic, with successive terms increasing by 0 or 1. So the sequence hits every positive integer.

This sequence can be obtained from the Hofstadter-Conway sequence A004001 using a construction of Isgur et al.

Links

Nathan Fox, Table of n, a(n) for n = 1..10000

A. Isgur, R. Lech, S. Moore, S. Tanny, Y. Verberne, and Y. Zhang, Constructing New Families of Nested Recursions with Slow Solutions, SIAM J. Discrete Math., 30(2), 2016, 1128-1147. (20 pages); DOI:10.1137/15M1040505

Maple

A285763:=proc(n) option remember: if n <= 0 then 0: elif n = 1 then 1: elif n = 2 then 2: elif n = 3 then 2: elif n = 4 then 2: elif n = 5 then 3: else A285763(A285763(n-2)) + A285763(n-A285763(n-2)): fi: end:

Mathematica

a[1] = 1; a[2] = a[3] = a[4] = 2; a[5] = 3; a[n_] := a[n] = a[a[n - 2]] + a[n - a[n - 2]]; Array[a, 64] (* Michael De Vlieger, Apr 26 2017 *)

Crossrefs

Cf. A004001, A285764.

Sequence in context: A126257 A025773 A308303 * A294621 A029077 A112176

Adjacent sequences: A285760 A285761 A285762 * A285764 A285765 A285766

Keyword

nonn

Author

Nathan Fox, Apr 25 2017

Status

approved