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
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
KEYWORD
nonn
AUTHOR
Nathan Fox, Apr 25 2017
STATUS
approved