A377606 Decimal expansion of -30*arcsin((5 - 4*sqrt(5))/15).

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

Offset

1,1

Comments

Dehn invariant of an icosidodecahedron with unit edge length and (negated) of a (small) rhombicosidodecahedron with unit edge length.

Links

Table of n, a(n) for n=1..90.

Eric Weisstein's World of Mathematics, Dehn Invariant.

Eric Weisstein's World of Mathematics, Icosidodecahedron.

Eric Weisstein's World of Mathematics, Small Rhombicosidodecahedron.

Index entries for transcendental numbers

Formula

Equals -30*arcsin((5 - 4*A002163)/15) = -30*arcsin((5 - A010532)/15).

Example

7.9824014167848074172162128505631888010390657928...

Mathematica

First[RealDigits[-30*ArcSin[(5 - Sqrt[80])/15], 10, 100]] (* or *)
First[RealDigits[PolyhedronData["Icosidodecahedron", "DehnInvariant"], 10, 100]]

Prog

(PARI) 30*asin((4*sqrt(5)-5)/15) \\ Charles R Greathouse IV, Nov 21 2024

Crossrefs

Cf. A002163, A010532.

Sequence in context: A342571 A372253 A256924 * A348668 A259069 A209328

Adjacent sequences: A377603 A377604 A377605 * A377607 A377608 A377609

Keyword

nonn,cons,easy

Author

Paolo Xausa, Nov 03 2024

Status

approved