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 A322645 Number of times the digit 4 appears in the first 10^n decimal digits of sqrt(2), sometimes called Pythagoras's constant, counting after the decimal point. 10

%I

%S 2,9,100,1016,10100,100024,1000126,10000054,100012725,1000008724

%N Number of times the digit 4 appears in the first 10^n decimal digits of sqrt(2), sometimes called Pythagoras's constant, counting after the decimal point.

%C It is not known if sqrt(2) is normal, but the distribution of decimal digits found for the first 10^n digits of sqrt(2) shows no statistically significant departure from a uniform distribution.

%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/PythagorassConstantDigits.html">Pythagoras's Constant Digits</a>.

%p a:=proc(n)

%p local digits, SQRT2, C, i;

%p digits:=10^n+100;

%p SQRT2:=convert(frac(evalf[digits](sqrt(2))),string)[2..digits-99];

%p C:=0;

%p for i from 1 to length(SQRT2) do

%p if SQRT2[i]="4" then C:=C+1; fi;

%p od;

%p return(C);

%p end;

%t Table[DigitCount[IntegerPart[(Sqrt[2]-1)*10^10^n], 10, 4], {n,1,10}] (* _Robert Price_, Mar 29 2019 *)

%Y Cf. A002193, A099294, A322641, A322642, A322643, A322644, A322646, A322647, A322648. A322649, A322650.

%K nonn,base,more

%O 1,1

%A _Martin Renner_, Dec 21 2018

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Last modified June 18 18:16 EDT 2021. Contains 345120 sequences. (Running on oeis4.)