A248832 The sum of denominators of unreduced mediants in Farey sequences of orders 1,2,..,n.
2, 6, 16, 34, 72, 122, 214, 338, 516, 734, 1062, 1438, 1970, 2586, 3322, 4186, 5322, 6566, 8152, 9898, 11896, 14114, 16838, 20254, 23982, 28196, 32746, 38108, 43710, 50242, 57286, 64990, 73238, 82326, 91846, 102698, 114234, 126706, 139818
Offset: 0
Examples
For n=4, the unreduced mediants are 1/2, 2/4, 5/10, 9/18, hence the sum of denominators is 2+4+10+18 = 34.
Links
- Wikipedia, Mediant.
- Wikipedia, Farey Sequence.
Formula
a(n) = 2*Sum_{k= 1,2,3,4..n} A213544(k).