A381155 Decimal expansion of the isoperimetric quotient of a regular 10-gon.

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

Offset: 0

Author

Paolo Xausa, Feb 15 2025

Keywords

• nonn
• cons
• easy

Comments

For the definition of isoperimetric quotient, see A381152.

Examples

			0.96688279904640254032818321918275298846986824108440...
		

Links

• Paolo Xausa, Table of n, a(n) for n = 0..10000
• Eric Weisstein's World of Mathematics, Isoperimetric Quotient.
• Wikipedia, Isoperimetric inequality.

Crossrefs

Cf. A019916, A178816.

Cf. isoperimetric quotient of other regular polygons: A073010 (triangle), A003881 (square), A381152 (pentagon), A093766 (hexagon), A381153 (heptagon), A196522 (octagon), A381154 (9-gon), A381156 (11-gon), A381157 (12-gon).

Programs

Mathematica

First[RealDigits[Pi/(10*Tan[Pi/10]), 10, 100]]

Formula

Equals Pi/(10*tan(Pi/10)) = Pi/(10*A019916).

Equals (1/25)*Pi*A178816.