cp's OEIS Frontend

A383690 Positions of digits in the decimal expansion of Pi where the cumulative sum of even digits equals the cumulative sum of odd digits (positions 1, 2, 3, ... refer to the digits 3, 1, 4, ...).

%I A383690 #30 May 20 2025 16:49:38
%S A383690 3,268,375,376,402
%N A383690 Positions of digits in the decimal expansion of Pi where the cumulative sum of even digits equals the cumulative sum of odd digits (positions 1, 2, 3, ... refer to the digits 3, 1, 4, ...).
%C A383690 Sequence is likely finite and 402 is likely the last term. If each digit in the decimal expansion of Pi appears with the same frequency and since the sum of the odd digits is 25 and the sum of the even digits is 20, then the difference between the cumulative sum of the odd digits and the cumulative sum of the even digits tends to be positive.
%C A383690 Sequence inspired by the discussion of Michael S. Branicky, Jinyuan Wang and David A. Corneth.
%e A383690 3 is in this sequence because when considering the first 3 decimal places in the decimal expansion of Pi, which are 3, 1 and 4, it is satisfied that 3 + 1 = 4.
%t A383690 p = RealDigits[Pi, 10, 10^4][[1]]; Flatten@ Position[ Accumulate[(-1)^p p], 0] (* _Giovanni Resta_, May 10 2025 *)
%Y A383690 Cf. A000796, A175813 (equal counts instead of equal sums).
%K A383690 nonn,base,more
%O A383690 1,1
%A A383690 _Gonzalo Martínez_, May 09 2025