A211879 - OEIS

%I #19 Feb 20 2014 08:54:59

%S 1,2,3,3,8,8,8,1,4,0,3,3,7,2,7,4,1,8,8,7,5,3,5,4,7,9,2,7,3,0,8,8,6,4,

%T 1,1,5,5,0,4,7,8,2,1,4,0,1,0,9,1,2,4,2,8,9,3,1,7,6,7,7,4,8,4,5,0,7,9,

%U 9,9,0,5,6,1,9,7,8,0,3,7,4,5,5,2,7,0,9,4,0,7,6,3,9,5,5,0,8,0,1,0,8,5,8,5,0,8,6,5,6,3,7,0,1,2,5,4

%N Decimal expansion of constant C such that 1 = Sum_{k>=1} 1/C^(k^3).

%e C = 1.2338881403372741887535479273...

%p Digits:= 120:

%p s:= convert(fsolve(sum(1/C^(k^3), k=1..infinity)=1, C=2)/10, string):

%p seq(parse(s[n+1]), n=1..116);  # _Alois P. Heinz_, Feb 13 2013

%t digits = 116; f[x_?NumericQ] := NSum[1/x^(k^3), {k, 1, Infinity}, WorkingPrecision -> digits]; x /. FindRoot[f[x] == 1, {x, 3/2, 1, 2}, WorkingPrecision -> digits] // RealDigits[#, 10, digits]& // First (* _Jean-François Alcover_, Feb 20 2014 *)

%Y Cf. A078975

%K cons,nonn

%O 1,2

%A _Balarka Sen_ and _Jimmy Zotos_, Feb 13 2013

%E More terms from _Alois P. Heinz_, Feb 13 2013