

A322722


Number of times the digit 7 appears in the first 10^n decimal digits of Euler's number e = exp(1), counting starts after the decimal point.


9




OFFSET

1,2


COMMENTS

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


LINKS

Eric Weisstein's World of Mathematics, e Digits.


MAPLE

a:=proc(n)
local digits, EXP1, C, i;
digits:=10^n+100;
EXP1:=convert(frac(evalf[digits](exp(1))), string)[2..digits99];
C:=0;
for i from 1 to length(EXP1) do
if EXP1[i]="7" then C:=C+1; fi;
od;
return(C);
end;


MATHEMATICA

Table[Count[IntegerDigits[IntegerPart[(E  2)*10^10^n]], 7], {n, 7}] (* Robert Price, Apr 07 2019 *)


CROSSREFS

Cf. A001113, A099298, A322648, A322715, A322716, A322717, A322718, A322719, A322720, A322721, A322723, A322724.


KEYWORD

nonn,base,more


AUTHOR



STATUS

approved



