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 A249022 #9 Oct 27 2014 20:50:52
%S A249022 4,6,6,5,9,9,3,0,6,2,0,3,7,2,9,2,6,5,2,2,1,7,3,4,2,2,0
%N A249022 Decimal expansion of Sine Euler constant.
%C A249022 The Sine Euler constant is introduced here as the limit as n increases without bound of sum{sin(1/k), k = 1..n} - integral{sin(1/x) over [1,n]}; this is analogous to the Euler constant, defined as the limit of sum{1/k, k = 1..n} - integral{1/x over [1,n]}.
%e A249022 Sine Euler constant = 0.466599306203729265221734220...
%t A249022 f = DifferenceRoot[Function[{\[FormalY], \[FormalN]}, {((2 \[FormalN] - z) (2 \[FormalN] - (z + 1))) \[FormalY][\[FormalN]] + \[FormalY][1 + \[FormalN]] == 0, \[FormalY][1] == -1}]];
%t A249022 (Total[Table[1/((-1)^(n + 1) (2 n - 1)!) HarmonicNumber[k, 2 n - 1], {n, 50}]] /. k -> #) - (CosIntegral[1] - CosIntegral[1/#] - Sin[1] + # Sin[1/#]) &[N[10^35, 40]]
%t A249022 RealDigits[t][[1]]
%t A249022 (* _Peter J. C. Moses_, Oct 20 2014 *)
%Y A249022 Cf. A001620 (Euler constant), A249023 (Tangent Euler constant).
%K A249022 nonn,easy,cons
%O A249022 0,1
%A A249022 _Clark Kimberling_, Oct 22 2014