OFFSET
1,2
LINKS
Clark Kimberling, Table of n, a(n) for n = 1..50
FORMULA
a(n) = c * 2^(n*(n+1)/2), where c = A048651 * A065442 = 0.4639944324508904477884... . - Vaclav Kotesovec, Oct 10 2016
MAPLE
SymmPolyn := proc(L::list, n::integer)
local c, a, sel;
a :=0 ;
sel := combinat[choose](nops(L), n) ;
for c in sel do
a := a+mul(L[e], e=c) ;
end do:
a;
end proc:
A203011 := proc(n)
local L, k ;
L := [seq(2^k-1, k=1..n)] ;
SymmPolyn(L, n-1) ;
end proc: # R. J. Mathar, Sep 23 2016
MATHEMATICA
f[k_] := -1 + 2^k; t[n_] := Table[f[k], {k, 1, n}]
a[n_] := SymmetricPolynomial[n - 1, t[n]]
Table[a[n], {n, 1, 16}] (* A203011 *)
Table[Product[2^k-1, {k, 1, n}] * Sum[1/(2^k-1), {k, 1, n}], {n, 1, 16}] (* Vaclav Kotesovec, Sep 06 2014 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Dec 29 2011
STATUS
approved