A196686 Number of odd digits of Pi minus number of even digits.

1, 2, 1, 2, 3, 4, 3, 2, 3, 4, 5, 4, 5, 6, 7, 8, 7, 8, 7, 6, 5, 4, 3, 2, 3, 4, 3, 4, 3, 4, 5, 6, 5, 4, 3, 2, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 10, 11, 12, 11, 12, 11, 10, 9, 10, 11, 10, 11, 10, 9, 10, 11, 10, 11, 10, 11, 10, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 2, 3, 2, 1, 0, -1, -2, -1, -2, -3, -4, -3, -2, -3, -4, -3, -2

Offset

1,2

Comments

Cumulative sum of A030657 with zeros replaced by "-1".

Links

Zak Seidov, Table of n, a(n) for n = 1..10000 [a(10000) corrected by Georg Fischer, Dec 29 2021]

Zak Seidov, Dependence a(n) for n = 1..10000

Zak Seidov, Dependence a(n) for n = 1..10^6

Example

Among first 10 digits of Pi, {3,1,4,1,5,9,2,6,5,3}, there are 7 odd and 3 even, hence a(10)=7-3=4.

Mathematica

rd=RealDigits[N[Pi, 10004]][[1]]; a=0; s=Reap[Do[a=a+2Mod[rd[[n]], 2]-1; Sow[{n, a}], {n, 10004}]][[2, 1]] (* this gives b-file *) (* Zak Seidov, Oct 05 2011 *)

Crossrefs

Cf. A030657, A175792 (negated), A175813 (indices of 0's).

Sequence in context: A202275 A030307 A175792 * A213088 A357564 A169809

Adjacent sequences: A196683 A196684 A196685 * A196687 A196688 A196689

Keyword

sign,base

Author

Zak Seidov, Oct 05 2011

Extensions

Definition amended by Georg Fischer, Dec 29 2021

Status

approved