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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
2, 9, 100, 1016, 10100, 100024, 1000126, 10000054, 100012725, 1000008724 (list; graph; refs; listen; history; text; internal format)
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..digits-99];

  C:=0;

  for i from 1 to length(SQRT2) do

    if SQRT2[i]="4" then C:=C+1; fi;

  od;

  return(C);

end;

MATHEMATICA

Table[DigitCount[IntegerPart[(Sqrt[2]-1)*10^10^n], 10, 4], {n, 1, 10}] (* Robert Price, Mar 29 2019 *)

CROSSREFS

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

Sequence in context: A227258 A027686 A187647 * A277180 A013520 A041239

Adjacent sequences:  A322642 A322643 A322644 * A322646 A322647 A322648

KEYWORD

nonn,base,more

AUTHOR

Martin Renner, Dec 21 2018

STATUS

approved

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Last modified August 4 13:38 EDT 2020. Contains 336201 sequences. (Running on oeis4.)