A240835 a(n)=1 for n <= s+k; thereafter a(n) = Sum_{i=0..k-1} a(n-i-s-a(n-i-1)) where s=0, k=4.

1, 1, 1, 1, 4, 4, 4, 4, 7, 7, 7, 10, 7, 10, 13, 10, 13, 13, 13, 16, 16, 16, 16, 16, 19, 19, 19, 22, 19, 22, 25, 22, 25, 25, 25, 28, 28, 28, 28, 31, 31, 31, 34, 31, 34, 37, 34, 37, 37, 34, 40, 40, 37, 43, 40, 40, 46, 43, 43, 46, 46, 46, 49, 49, 46, 52, 52, 49, 55, 52, 52, 58, 55, 55, 58, 55, 58, 61, 58, 61, 61, 61

Offset: 1

Author

N. J. A. Sloane, Apr 16 2014

Keywords

• nonn
• hear

Links

• N. J. A. Sloane, Table of n, a(n) for n = 1..20000
• Joseph Callaghan, John J. Chew III, and Stephen M. Tanny, On the behavior of a family of meta-Fibonacci sequences, SIAM Journal on Discrete Mathematics 18.4 (2005): 794-824. See Eq. (1.7) and Table 6.1
• Index entries for Hofstadter-type sequences

Crossrefs

Callaghan et al. (2005)'s sequences T_{0,k}(n) for k=1 through 7 are A000012, A046699, A046702, A240835, A241154, A241155, A240830.

Programs

Maple

#T_s,k(n) from Callaghan et al. Eq. (1.7).
s:=0; k:=4;
a:=proc(n) option remember; global s,k;
if n <= s+k then 1
else
    add(a(n-i-s-a(n-i-1)),i=0..k-1);
fi; end;
t1:=[seq(a(n),n=1..100)];

Mathematica

A240835[n_]:=A240835[n]=If[n<=4,1,Sum[A240835[n-i-A240835[n-i-1]],{i,0,3}]];
Array[A240835,100] (* Paolo Xausa, Dec 06 2023 *)