A317015 a(n) = n for n < 2, a(n) = a(freq(a(n-1),n)) + a(freq(a(n-2),n)) for n >= 2, where freq(i, j) is the number of times i appears in the first j terms.

0, 1, 2, 2, 4, 3, 2, 3, 4, 4, 4, 8, 5, 2, 5, 6, 3, 3, 8, 6, 4, 5, 5, 8, 6, 4, 4, 6, 7, 5, 4, 7, 6, 5, 5, 6, 5, 6, 7, 5, 6, 8, 8, 6, 7, 8, 6, 6, 16, 9, 2, 4, 7, 7, 4, 6, 9, 7, 5, 7, 8, 7, 7, 8, 8, 8, 8, 16, 10, 3, 4, 11, 9, 3, 4, 7, 13, 9, 5, 12, 9, 4, 5, 7, 10, 7, 4, 7, 10, 7, 8, 11, 7, 5, 5, 10, 9

Offset

0,3

Comments

Inspired by A316774.

Let b(n) = n for n < 3, b(n) = b(freq(b(n-1),n)) for n >= 3, where freq(i, j) is the number of times i appears in the first j terms and b(n) has offset 0. For n >= 1, b(n) - 1 are 0, 1, 0, 1, 1, 0, 0, 1, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, ... (cf. A093879). While b(n) has one parent spot, this entry (a(n)) has two parent spots which are freq(a(n-1),n) and freq(a(n-2),n).

Links

Alois P. Heinz, Table of n, a(n) for n = 0..65536

Maple

b:= proc() 0 end:
a:= proc(n) option remember; local t;
      t:= `if`(n<2, n, a(b(a(n-1)))+a(b(a(n-2))));
      b(t):= b(t)+1; t
    end:
seq(a(n), n=0..200);  # Alois P. Heinz, Jul 19 2018

Mathematica

Nest[Append[#, #[[Count[#, #[[-1]] ] + 1]] + #[[Count[#, #[[-2]] ] + 1 ]] ] &, {0, 1}, 95] (* Michael De Vlieger, Jul 20 2018 *)

Crossrefs

Cf. A316774.

Sequence in context: A098086 A332887 A306323 * A341902 A175681 A161003

Adjacent sequences: A317012 A317013 A317014 * A317016 A317017 A317018

Keyword

nonn

Author

Altug Alkan, Jul 19 2018

Status

approved