cp's OEIS Frontend

A244647 Decimal expansion of the sum of the reciprocals of the decagonal numbers (A001107).

%I A244647 #20 Feb 08 2023 23:03:11
%S A244647 1,2,1,6,7,4,5,9,5,6,1,5,8,2,4,4,1,8,2,4,9,4,3,3,9,3,5,2,0,0,4,7,6,0,
%T A244647 3,8,2,1,0,8,3,6,1,7,0,0,9,2,2,7,7,2,8,9,0,9,4,9,8,3,7,4,4,1,5,4,4,6,
%U A244647 9,6,3,5,6,3,5,0,7,2,9,5,4,8,7,1,0,5,3,5,7,9,7,8,8,6,7,7,1,5,3,2,2,0,5,6,9
%N A244647 Decimal expansion of the sum of the reciprocals of the decagonal numbers (A001107).
%C A244647 For the partial sums of the reciprocals of the (positive) decagonal numbers see A250551(n+1)/A294515(n), n >= 0. - _Wolfdieter Lang_, Nov 07 2017
%H A244647 Wikipedia, <a href="http://en.wikipedia.org/wiki/Polygonal_number">Polygonal number</a>
%F A244647 Sum_{n>0} 1/(4n^2 - 3n) = log(2) + Pi/6, (A002162 + A019673).
%e A244647 1.216745956158244182494339352004760382108361700922772890949837441544696356350....
%t A244647 RealDigits[ Log[2] + Pi/6, 10, 111][[1]] (* or *)
%t A244647 RealDigits[ Sum[1/(4n^2 - 3n), {n, 1 , Infinity}], 10, 111][[1]]
%o A244647 (PARI) log(2)+Pi/6 \\ _Charles R Greathouse IV_, Feb 08 2023
%Y A244647 Cf. A001107, A000038, A013661, A244639, A016627, A244645, A244646, A244648, A244649, A250551(n+1)/A294515(n).
%K A244647 nonn,cons,easy
%O A244647 1,2
%A A244647 _Robert G. Wilson v_, Jul 03 2014