OFFSET
0,1
COMMENTS
EXAMPLE
1/6 + 1/9 + 1/13 + ... = (1/276)*(-161 + 48r*tanh(r/2), where r=(pi/2)sqrt(23).
1/6 + 1/9 + 1/13 + ... = 0.726800619464935778179143007194435...
MATHEMATICA
$MaxExtraPrecision = Infinity; t[n_, k_] := t[n, k] = n + (n + k - 2) (n + k - 1)/2; u = N[Sum[1/t[3, k], {k, 1, Infinity}], 130]; RealDigits[u, 10]
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Aug 06 2013
STATUS
approved