

A322643


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


10




OFFSET

1,1


COMMENTS

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.


LINKS

Table of n, a(n) for n=1..10.
Eric Weisstein's World of Mathematics, Pythagoras's Constant Digits.


MAPLE

a:=proc(n)
local digits, SQRT2, C, i;
digits:=10^n+100;
SQRT2:=convert(frac(evalf[digits](sqrt(2))), string)[2..digits99];
C:=0;
for i from 1 to length(SQRT2) do
if SQRT2[i]="2" then C:=C+1; fi;
od;
return(C);
end;


MATHEMATICA

Table[DigitCount[IntegerPart[(Sqrt[2]1)*10^10^n], 10, 2], {n, 1, 10}] (* Robert Price, Mar 29 2019 *)


CROSSREFS

Cf. A002193, A099293, A322641, A322642, A322644, A322645, A322646, A322647, A322648, A322649, A322650.
Sequence in context: A256398 A008926 A136468 * A178171 A132523 A012554
Adjacent sequences: A322640 A322641 A322642 * A322644 A322645 A322646


KEYWORD

nonn,base,more


AUTHOR

Martin Renner, Dec 21 2018


STATUS

approved



