OFFSET
0,6
COMMENTS
Two positive integers are divisible if the first divides the second, and have a binary carry if the positions of 1's in their reversed binary expansion overlap.
FORMULA
a(n) = A325124(n) - n.
EXAMPLE
The a(3) = 1 through a(12) = 11 pairs:
{1,3} {1,3} {1,3} {1,3} {1,3} {1,3} {1,3} {1,3} {1,3} {1,3}
{1,5} {1,5} {1,5} {1,5} {1,5} {1,5} {1,5} {1,5}
{2,6} {1,7} {1,7} {1,7} {1,7} {1,7} {1,7}
{3,6} {2,6} {2,6} {1,9} {1,9} {1,9} {1,9}
{3,6} {3,6} {2,6} {2,6} {2,6} {2,6}
{3,6} {3,6} {3,6} {3,6}
{3,9} {3,9} {3,9} {3,9}
{2,10} {1,11} {1,11}
{2,10} {2,10}
{4,12}
{6,12}
MATHEMATICA
Table[Length[Select[Subsets[Range[n], {2}], Divisible@@Reverse[#]&&Intersection[Position[Reverse[IntegerDigits[#[[1]], 2]], 1], Position[Reverse[IntegerDigits[#[[2]], 2]], 1]]!={}&]], {n, 0, 20}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Gus Wiseman, Mar 29 2019
STATUS
approved