OFFSET

1,2

COMMENTS

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..8192

Sean A. Irvine, Java program (github)

Rémy Sigrist, PARI program

Wikipedia, Stack (abstract data type)

FORMULA

a(n) = 1 iff n is odd.

a(A020989(k)) = k + 1 for any k >= 0.

EXAMPLE

The first terms, alongside the binary representation of n and the evolution of stack S, are:

n a(n) bin(n) S

- ---- ------ -------------------------------------------------

1 1 1 () -> (1)

2 2 10 (1) -> (1,1) -> (2)

3 1 11 (2) -> (2,1) -> (2,1,1)

4 3 100 (2,1,1) -> (2,1,1,1) -> (2,1,2) -> (2,3)

5 1 101 (2,3) -> (2,3,1) -> (2,4) -> (2,4,1)

6 2 110 (2,4,1) -> (2,4,1,1) -> (2,4,1,1,1) -> (2,4,1,2)

PROG

(Java) See Links section.

(PARI) See Links section.

CROSSREFS

KEYWORD

AUTHOR

Rémy Sigrist, Jun 07 2019

STATUS

approved