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Decimal expansion of 4*sqrt(5 + 2*sqrt(5)).
4

%I #4 May 11 2021 18:21:25

%S 1,2,3,1,0,7,3,4,1,4,8,7,0,1,0,1,3,6,1,0,2,8,1,1,6,2,3,0,4,1,4,7,6,3,

%T 9,2,9,6,0,2,6,8,0,8,5,7,4,1,5,1,1,6,9,7,0,8,1,5,6,6,2,5,0,0,1,4,9,9,

%U 4,5,3,1,5,3,9,8,0,3,6,3,6,7,3,8,1,8,3,7,4,8,8,6,6

%N Decimal expansion of 4*sqrt(5 + 2*sqrt(5)).

%C Decimal expansion of the volume of a rhombic triacontahedron with unit edge length.

%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Rhombic_triacontahedron">Rhombic triacontahedron</a>

%e 12.310734148701013610281...

%t RealDigits[4 Sqrt[5 + 2 Sqrt[5]], 10, 100][[1]] // Flatten

%Y Cf. A344171 (rhombic triacontahedron surface area).

%Y Cf. A344212 (rhombic triacontahedron midradius).

%Y Cf. A019952 (rhombic triacontahedron radius of inscribed sphere).

%K nonn,cons

%O 2,2

%A _Wesley Ivan Hurt_, May 10 2021