This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A228045 #16 Feb 24 2025 04:07:47
%S A228045 7,2,6,8,0,0,6,1,9,4,6,4,9,3,5,7,7,8,1,7,9,1,4,3,0,0,7,1,9,4,4,3,5,3,
%T A228045 8,3,9,0,8,7,7,4,6,2,7,6,3,6,0,7,7,7,3,2,3,8,9,9,7,2,6,1,3,4,0,1,3,4,
%U A228045 6,7,2,7,2,0,1,4,8,5,9,5,2,6,4,2,6,4
%N A228045 Decimal expansion of sum of reciprocals of row 3 of the natural number array, A185787.
%C A228045 See A228044.
%F A228045 Equals 1/6 + 1/9 + 1/13 + ...
%F A228045 Equals (1/276)*(-161 + 48*r*tanh(r)), where r = (Pi/2)*sqrt(23).
%e A228045 0.726800619464935778179143007194435...
%t A228045 $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]
%Y A228045 Cf. A185787, A000027, A228044, A226985.
%K A228045 nonn,cons,easy
%O A228045 0,1
%A A228045 _Clark Kimberling_, Aug 06 2013