A120137 a(n) = 8 + floor( (1 + Sum_{j=1..n-1} a(j)) / 2).

8, 12, 18, 27, 41, 61, 92, 138, 207, 310, 465, 698, 1047, 1570, 2355, 3533, 5299, 7949, 11923, 17885, 26827, 40241, 60361, 90542, 135813, 203719, 305579, 458368, 687552, 1031328, 1546992, 2320488, 3480732, 5221098, 7831647, 11747471, 17621206

Offset: 1

Author

Graeme McRae, Jun 10 2006

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A073941, A072493, A112088, A120134 - A120136, A120138 - A120209.

Programs

Mathematica

a[n_]:= a[n]= 8 +Floor[(1 +Sum[a[k], {k,n-1}])/2];
Table[a[n], {n,60}] (* G. C. Greubel, May 08 2023 *)
nxt[{t_,a_}]:=Module[{c=8+Floor[(1+t)/2]},{t+c,c}]; NestList[nxt,{8,8},40][[;;,2]] (* Harvey P. Dale, Sep 10 2023 *)

SageMath

@CachedFunction
def A120137(n): return 8 +(1 +sum(A120137(k) for k in range(1,n)))//2
[A120137(n) for n in range(1,60)] # G. C. Greubel, May 08 2023