A031248 a(n)=(# 1's)-(# 2's) in first n terms of A031235.

1, 0, 0, 0, 0, 1, 2, 3, 2, 3, 3, 4, 4, 5, 5, 4, 5, 4, 3, 2, 2, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 3, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 6, 7, 8, 9, 10, 9, 10, 11, 11, 12, 13, 13, 14, 15, 15, 14, 15, 16, 15, 16, 15, 14

Offset: 1

Author

Clark Kimberling

Keywords

• nonn

Programs

Mathematica

Accumulate[Which[#==1,1,#==2,-1,True,0]&/@(Reverse[IntegerDigits[ #,5]]&/@ Range[ 0,40]//Flatten)] (* Harvey P. Dale, Aug 02 2016 *)