cp's OEIS Frontend

A037001 Positions of the digit '2' in the decimal expansion of Pi (where positions 0, 1, 2,... refer to the digits 3, 1, 4,...).

%I A037001 #26 Feb 16 2025 08:32:37
%S A037001 6,16,21,28,33,53,63,73,76,83,89,93,102,112,114,135,136,140,149,160,
%T A037001 165,173,185,186,203,221,229,241,244,260,275,280,289,292,298,302,326,
%U A037001 329,333,335,337,354,374,380,406,423,435,456,462,477,479,484,485,500
%N A037001 Positions of the digit '2' in the decimal expansion of Pi (where positions 0, 1, 2,... refer to the digits 3, 1, 4,...).
%C A037001 The first few primes in this sequence are 53, 73, 83, 89, 149, 173, 229, 241, 337, 479, 571, 613, 661, 757, 829, 877, 911, 977, 991, ... - _M. F. Hasler_, Jul 28 2024
%H A037001 Amiram Eldar, <a href="/A037001/b037001.txt">Table of n, a(n) for n = 1..10000</a>
%H A037001 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/PiDigits.html">Pi Digits.</a>
%H A037001 <a href="/index/Ph#Pi314">OEIS index to sequences related to Pi</a>.
%F A037001 a(n) ~ 10*n if Pi is normal, as generally assumed. - _M. F. Hasler_, Jul 28 2024
%t A037001 Flatten @ Position[ RealDigits[Pi - 3, 10, 500][[1]], 2] (* _Robert G. Wilson v_, Mar 07 2011 *)
%o A037001 (PARI) A037001_upto(N=999, d=2)={localprec(N+20); [i-1|i<-[1..#N=digits(Pi\10^-N)], N[i]==d]} \\ _M. F. Hasler_, Jul 28 2024
%Y A037001 Cf. A000796 (decimal expansion (or digits) of Pi).
%Y A037001 Cf. A053746 (= a(n) + 1: the same with different offset).
%Y A037001 Cf. A037000, A037002, A037003, A037004, A037005, A036974, A037006, A037007, A037008 (similar for digits 1, ..., 9 and 0).
%Y A037001 Cf. A035117 (first occurrence of at least n '1's), A050281 (n '2's), A050282, A050283, A050284, A050286, A050287, A048940 (n '9's).
%Y A037001 Cf. A096755 (first occurrence of exactly n '1's), A096756, A096757, A096758, A096759, A096760, A096761, A096762, A096763 (exactly n '9's), A050279 (exactly n '0's).
%Y A037001 Cf. A121280 = A068987 - 1: position of "123...n" in Pi's decimals.
%Y A037001 Cf. A176341: first occurrence of n in Pi's digits.
%K A037001 nonn,base
%O A037001 1,1
%A A037001 Nicolau C. Saldanha (nicolau(AT)mat.puc-rio.br)