Summation of series defined by counting blocks of digits

Abstract We discuss the summation of certain series defined by counting blocks of digits in the B -ary expansion of an integer. For example, if s 2 ( n ) denotes the sum of the base-2 digits of n , we show that ∑ n ⩾ 1 s 2 ( n ) / ( 2 n ( 2 n + 1 ) ) = ( γ + log 4 π ) / 2 . We recover this previous result of Sondow and provide several generalizations.