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A248832 The sum of denominators of unreduced mediants in Farey sequences of orders 1,2,..,n. 0
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..38.

Wikipedia, Mediant.

Wikipedia, Farey Sequence.

FORMULA

a(n) = 2*Sum_{k= 1,2,3,4..n} A213544(k).

EXAMPLE

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.

CROSSREFS

Cf. A007306, A006843.

Sequence in context: A309691 A235792 A192706 * A280400 A199477 A330884

Adjacent sequences: A248829 A248830 A248831 * A248833 A248834 A248835

KEYWORD

nonn,easy

AUTHOR

Nehul Yadav, Oct 15 2014

STATUS

approved

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Last modified January 28 20:13 EST 2023. Contains 359905 sequences. (Running on oeis4.)