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Number of times the digit 5 appears in the first 10^n digits of Pi.
12

%I #4 Feb 16 2025 08:32:55

%S 3,8,97,1046,10026,100359,1000466,9993478,99998885,1000007928,

%T 9999963661,99999671008

%N Number of times the digit 5 appears in the first 10^n digits of Pi.

%D Alfred S. Posamentier & Ingmar Lehmann, A Biography of the World's Most Mysterious Number, Prometheus Books, Amherst, NY 2004, page 129.

%H Kanada Laboratory, <a href="http://www.super-computing.org/pi-decimal_current.html">Statistical Distribution Information</a>.

%H Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PiDigits.html">Pi Digits</a>

%t $MaxPrecision = 1100000; dp = Drop[ RealDigits[Pi, 10, 1000010] [[1]], 1]; Table[ Count[ Take[dp, 10^n], 5], {n, 6}]

%Y Cf. A099291, A099292, A099293, A099294, A099295, A099297, A099298, A099299, A099300.

%K nonn,base,changed

%O 1,1

%A _Robert G. Wilson v_, Oct 11 2004