OFFSET
0,1
COMMENTS
EXAMPLE
1/15 + 1/20 + 1/26 + ... = (1/17160)(-9997 + 1760r*tanh(r)), where r = (pi/2)*sqrt(39)
1/15 + 1/20 + 1/26 + ... = 0.42353909960870019683760768997442893...
MATHEMATICA
$MaxExtraPrecision = Infinity; t[n_, k_] := t[n, k] = n + (n + k - 2) (n + k - 1)/2; u = N[Sum[1/t[5, k], {k, 1, Infinity}], 130]; RealDigits[u, 10]
PROG
(PARI) sumnumrat(1/(n*(n+7)/2+11), 1) \\ Charles R Greathouse IV, Feb 08 2023
CROSSREFS
KEYWORD
AUTHOR
Clark Kimberling, Aug 06 2013
STATUS
approved