OFFSET
1,3
EXAMPLE
20 in binary is 10100. Compare this with its digit reversal, 00101. XOR each pair of corresponding digits: 1 XOR 0 = 1, 0 XOR 0 = 0, 1 XOR 1 = 0, 0 XOR 0 = 0, 0 XOR 1 = 1. There are three bit pairs that contain the same values, so a(20) = 3.
MAPLE
A144079 := proc(n) local a, dgs, i; a := 0 ; dgs := convert(n, base, 2) ; for i from 1 to nops(dgs) do if op(i, dgs)+op(-i, dgs) <> 1 then a := a+1 ; fi; od; RETURN(a) ; end: for n from 1 to 240 do printf("%d, ", A144079(n)) ; od: # R. J. Mathar, Sep 14 2008
MATHEMATICA
Table[With[{c=IntegerDigits[n, 2]}, Count[BitXor[c, Reverse[c]], 0]], {n, 110}] (* Harvey P. Dale, Sep 03 2015 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Leroy Quet, Sep 09 2008
EXTENSIONS
More terms from R. J. Mathar, Sep 14 2008
STATUS
approved