A198759 The number of pairs of braces to note the properly nested set with n elements.

1, 2, 4, 7, 11, 15, 20, 25, 30, 36, 42, 48, 54, 60, 66, 73, 80, 87, 94, 101, 108, 115, 122, 129, 136, 143, 150, 158, 166, 174, 182, 190, 198, 206, 214, 222, 230, 238, 246, 254, 262, 270, 278, 286, 294, 302, 310, 318, 326, 334, 342, 350, 359, 368, 377, 386, 395

Offset: 0

Author

R. J. Mathar, Oct 29 2011

Keywords

• nonn

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..20000
• F. T. Adams-Watters, Re: Set of sets using minimal number of braces, SeqFan Oct 29 2011
• J. Zucker, Set of sets using minimal number of braces, SeqFan Oct 25 2011

Crossrefs

Cf. A004111.

Programs

Maple

# implementing the Adams-Watters partial sum formula up to nmax elements
read("transforms") ;
nmax := 40 ;
a004111rep := [1,1] ;
n := 2 ;
while nops(a004111rep) < nmax do
        a004111rep := [op(a004111rep),seq(n,i=1..A004111(n))] ;
        n := n+1 ;
end do:
PSUM(a004111rep) ;