0,1

The Winkel tripel projection is the average of the Aitoff projection and an equirectangular projection. The latter component depends on a standard parallel which in radians is this constant.

Table of n, a(n) for n=0..101.

Mike Bostock, Winkel Tripel

Wikipedia, Winkel tripel projection

0.88068923542035666722694378256890...

First@ RealDigits@ N[ArcCos[2/Pi], 120] (* Michael De Vlieger, Aug 06 2016 *)

(PARI) acos(2/Pi)

Cf. A060294 (2/Pi), A232247 (arctan(2/Pi)).

Sequence in context: A321096 A243508 A144802 * A019960 A069527 A154492

Adjacent sequences: A275474 A275475 A275476 * A275478 A275479 A275480

nonn,cons

Jeremy Tan, Jul 29 2016

approved