Right Boundary Segment N

The segment numbers which are the right boundary, being the X axis and notches there, are

FIXME:

N such that N+2 in base-4 has
  least significant digit any 0,1,2,3
  above that only digits 0,2

= 0,1, 2,3,4,5, 14,15,16,17, 18,19,20,21, 62,63,64,65, ...

Left Boundary Segment N

The segment numbers which are the left boundary of the curve continued infinitely, being the stair-step diagonal, are

FIXME:

N such that N+1 in base-4 has
  least significant digit any 0,1,2,3
  above that only digits 0,2

= 0,1,2, 7,8,9,10, 31,32,33,34, 39,40,41,42, 127,128,129,130, ...