%I #23 Jul 29 2024 06:13:00

%S 2,4,38,41,50,69,95,96,104,111,139,149,154,155,156,164,169,175,176,

%T 199,207,221,239,244,247,251,270,282,296,298,315,320,325,343,345,363,

%U 364,382,386,391,394,396,397,418

%N Positions of '1's in the decimal expansion of Pi (where positions 1,2,3,... refer to the digits 3,1,4,...).

%H Vincenzo Librandi, <a href="/A053745/b053745.txt">Table of n, a(n) for n = 1..1000</a>

%H <a href="/index/Ph#Pi314">Index entries for sequences related to the number Pi</a>

%F a(n) = 1 + A037000(n), a variant where position 1 is the first digit after the decimal point. - _M. F. Hasler_, Mar 20 2017

%F a(n) ~ 10*n if Pi is normal (as generally assumed but yet unproved). - _M. F. Hasler_, Jul 29 2024

%t Flatten[Position[RealDigits[Pi, 10, 1000][[1]], 1]] (* _Vincenzo Librandi_, Oct 07 2013 *)

%o (PARI) A053745_upto(N=444, d=1)={localprec(N+20); [i|i<-[1..#N=digits(Pi\10^-N)], N[i]==d]} \\ _M. F. Hasler_, Jul 29 2024, replacing earlier code from 2017

%Y Cf. A014976, A053746 - A053753 (the same for digits 0, ..., 9).

%Y Cf. A088565 (primes in this sequence), A000796 (decimal digits of Pi).

%K nonn,base

%O 1,1

%A _Simon Plouffe_, Feb 20 2000