A122143 Decimal expansion of Sum_{k >= 1} cos(k)/k^2.

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

Offset

0,1

Comments

Also, decimal expansion of the real part of Sum_{k>=1} e^(i*k)/k^2. [Bruno Berselli, Mar 24 2013]

Links

Table of n, a(n) for n=0..103.

Formula

Equals (2*Pi*(Pi-3)+3)/12.

Example

0.324137740053329817241093475006273747120365201519245527248085933216...

Mathematica

Print[x=FullSimplify[Sum[Cos[n]/n^2, {n, Infinity}]]]; RealDigits[N[x, 110]][[1]]

Prog

(PARI) (2*Pi*(Pi-3)+3)/12 \\ Jianing Song, Nov 09 2019

Crossrefs

Cf. A096418 (decimal expansion of Sum_{k >= 1} sin(k)/k^2).

Cf. A263192, A121225.

Sequence in context: A123359 A121885 A187760 * A144868 A134029 A117623

Adjacent sequences: A122140 A122141 A122142 * A122144 A122145 A122146

Keyword

nonn,cons

Author

T. D. Noe, Aug 28 2006

Status

approved