OFFSET
1,2
COMMENTS
The terms can also be interpreted as numbers k such that a walk on the square lattice governed by the quaternary digits of Pi is at the origin after k steps, where digit 0 corresponds to a step to the right, 1 to up, 2 to left, and 3 to down.
There are no more terms below 2*10^9.
There are two variations of this sequence, according to the directions each digit corresponds to. In A339450, 0=right, 1=left, 2=up, 3=down. For the case 0=right, 1=up, 2=down, 3=left, the only terms below 2*10^9 are 0, 2, 4, 8.
EXAMPLE
4 is a term because the first four quaternary digits of Pi are 3, 0, 2, 1, one of each digit.
386 is a term because among the first 386 digits there are 99 0's and 99 2's, and 94 1's and 94 3's.
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Pontus von Brömssen, Dec 05 2020
STATUS
approved