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 A197723 Decimal expansion of (3/2)*Pi. 12
 4, 7, 1, 2, 3, 8, 8, 9, 8, 0, 3, 8, 4, 6, 8, 9, 8, 5, 7, 6, 9, 3, 9, 6, 5, 0, 7, 4, 9, 1, 9, 2, 5, 4, 3, 2, 6, 2, 9, 5, 7, 5, 4, 0, 9, 9, 0, 6, 2, 6, 5, 8, 7, 3, 1, 4, 6, 2, 4, 1, 6, 8, 8, 8, 4, 6, 1, 7, 2, 4, 6, 0, 9, 4, 2, 9, 3, 1, 3, 4, 9, 7, 9, 4, 2, 0, 5, 2, 2, 3, 8, 0, 1, 3, 1, 7, 5, 6, 0, 1, 9, 7, 3, 2, 2 (list; constant; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS As radians, this is equal to 270 degrees or 300 gradians. Multiplying a number by -i (with i being the imaginary unit sqrt(-1)) is equivalent to rotating it by this amount on the complex plane. Named 'Pau' by Randall Munroe, as a humorous compromise between Pi and Tau. - Orson R. L. Peters, Jan 08 2017 (3*Pi/2)*a^2 is the area of the cardioid whose polar equation is r = a*(1+cos(t)) and whose Cartesian equation is (x^2+y^2-a*x)^2 = a^2*(x^2+y^2). The length of this cardioid is 8*a. See the curve at the Mathcurve link. - Bernard Schott, Jan 29 2020 LINKS Ivan Panchenko, Table of n, a(n) for n = 1..1000 Robert Ferréol, Cardioid, Mathcurve. Randall Munroe, xkcd: Pi vs. Tau Eric Weisstein's World of Mathematics, Cardioid FORMULA 2*Pi - Pi/2 = Pi + Pi/2. Equals Integral_{t=0..Pi} (1+cos(t))^2 dt. - Bernard Schott, Jan 29 2020 Equals -4 + Sum_{k>=1} (k+1)*2^k/binomial(2*k,k). - Amiram Eldar, Aug 19 2020 EXAMPLE 4.712388980384689857693965074919254326296... MAPLE Digits:=100: evalf(3*Pi/2); # Wesley Ivan Hurt, Jan 08 2017 MATHEMATICA RealDigits[3Pi/2, 10, 105][] PROG (PARI) 3*Pi/2 \\ Charles R Greathouse IV, Jul 06 2018 CROSSREFS Cf. A019669, A003881, A347152. Sequence in context: A021959 A188735 A254338 * A186191 A256507 A123734 Adjacent sequences:  A197720 A197721 A197722 * A197724 A197725 A197726 KEYWORD nonn,cons AUTHOR Alonso del Arte, Oct 17 2011 STATUS approved

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Last modified January 24 00:05 EST 2022. Contains 350515 sequences. (Running on oeis4.)