289613

Appears in sequences

• Let v = list of denominators of Farey series of order n (see A006843); let b(n) = Sum 1/(k*k'*(k+k')), where (k,k') are pairs of successive terms of v; a(n) = numerator of b(n).at n=9A278047
• a(0) = a(1) = 1; a(n) = a(n-2) + Sum_{k=0..n-2} binomial(n-2,k) * a(k).at n=13A332885