A005468 a(n) = 1 + a(floor(n/2))*a(ceiling(n/2)).

1, 2, 3, 5, 7, 10, 16, 26, 36, 50, 71, 101, 161, 257, 417, 677, 937, 1297, 1801, 2501, 3551, 5042, 7172, 10202, 16262, 25922, 41378, 66050, 107170, 173890, 282310, 458330, 634350, 877970, 1215290, 1682210, 2335898, 3243602, 4504302, 6255002

Offset: 1

Author

Colin Mallows

Keywords

• nonn
• easy

References

• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..5000

Programs

Maple

a:= proc(n) option remember; `if`(n<2, n,
      1+(t->a(t)*a(n-t))(iquo(n, 2)))
    end:
seq(a(n), n=1..50);  # Alois P. Heinz, Jun 24 2016

PARI

v=vector(60);v[1]=1;for(k=2,60,v[k]=v[k\2]*v[(k+1)\2]+1);v \\ Franklin T. Adams-Watters, Apr 22 2009

Extensions

More terms from Franklin T. Adams-Watters, Apr 22 2009