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A375189
Decimal expansion of the sagitta of a regular 10-gon with unit side length.
8
7, 9, 1, 9, 2, 2, 2, 0, 1, 6, 2, 2, 6, 8, 1, 4, 6, 9, 1, 9, 4, 4, 1, 5, 4, 6, 3, 4, 7, 1, 8, 3, 2, 0, 5, 7, 1, 6, 9, 5, 8, 1, 0, 8, 0, 3, 6, 8, 6, 6, 6, 4, 8, 6, 1, 5, 8, 7, 0, 4, 9, 7, 5, 1, 7, 8, 2, 8, 8, 1, 8, 5, 7, 1, 3, 5, 6, 9, 9, 0, 4, 7, 9, 9, 1, 0, 3, 4, 3, 3
OFFSET
-1,1
LINKS
Eric Weisstein's World of Mathematics, Regular Polygon.
Eric Weisstein's World of Mathematics, Sagitta
FORMULA
Equals tan(Pi/20)/2 = A019907/2.
Equals (1 + sqrt(5) - sqrt(5 + 2*sqrt(5)))/2.
Equals A001622 - A179452.
EXAMPLE
0.0791922201622681469194415463471832057169581080...
MATHEMATICA
First[RealDigits[Tan[Pi/20]/2, 10, 100]]
CROSSREFS
Cf. A001622 (circumradius), A179452 (apothem), A178816 (area).
Cf. sagitta of other polygons with unit side length: A020769 (triangle), A174968 (square), A375068 (pentagon), A375069 (hexagon), A374972 (heptagon), A375070 (octagon), A256853 (9-gon), A375192 (11-gon), A375194 (12-gon).
Cf. A019907.
Sequence in context: A132806 A016629 A154203 * A055676 A296500 A202323
KEYWORD
nonn,cons,easy
AUTHOR
Paolo Xausa, Aug 04 2024
STATUS
approved