OFFSET
0,1
COMMENTS
See A190404.
LINKS
Danny Rorabaugh, Table of n, a(n) for n = 0..500
EXAMPLE
0.85635039560977957398146182399142454489929399971437975...
MATHEMATICA
f[i_, j_] := i + (j + i - 2)(j + i - 1)/2; (* natural number array, A000027 *)
g[i_, j_] := (1/2)^f[i, j];
d[h_] := Sum[g[i, i+h-1], {i, 1, 250}]; (* h-th up-diag sum *)
e[h_] := Sum[g[i+h, i], {i, 1, 250}]; (* h-th low-diag sum *)
c1 = N[Sum[d[j], {j, 1, 30}], 50]
RealDigits[c1, 10, 50, -1] (* A190412 *)
c2 = N[Sum[e[i], {i, 1, 30}], 50]
RealDigits[c2, 10, 50, -1] (* A190415 *)
c1 + c2 (* very close to 1 *)
PROG
(Sage)
def A190412(b): # Generate the constant with b bits of precision
return N(sum([sum([(1/2)^(i+(j+2*i-3)*(j+2*i-2)/2) for i in range(1, b)]) for j in range(1, b)]), b)
A190412(365) # Danny Rorabaugh, Mar 26 2015
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Clark Kimberling, May 10 2011
EXTENSIONS
a(49) corrected and a(50)-a(105) added by Danny Rorabaugh, Mar 24 2015
STATUS
approved