A228046 Decimal expansion of sum of reciprocals of row 4 of the natural number array, A185787.

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

Offset

0,1

Comments

See A228044.

Links

Table of n, a(n) for n=0..85.

Formula

Equals 1/10 + 1/14 + 1/19 + ...

Equals (1/4340)*(-2573 + 560*r*tanh(r)), where r = (Pi/2)*sqrt(31).

Example

0.5356361947807872845578507486647...

Mathematica

$MaxExtraPrecision = Infinity; t[n_, k_] := t[n, k] = n + (n + k - 2) (n + k - 1)/2; u = N[Sum[1/t[4, k], {k, 1, Infinity}], 130]; RealDigits[u, 10]

Crossrefs

Cf. A185787, A000027, A228044, A226985.

Sequence in context: A073316 A245979 A277621 * A092516 A269893 A336055

Adjacent sequences: A228043 A228044 A228045 * A228047 A228048 A228049

Keyword

nonn,cons,easy,changed

Author

Clark Kimberling, Aug 06 2013

Status

approved