59. First prove
Hk⩽k(k+1)24(a1+4a2+⋯+k2ak)
By the Cauchy-Schwarz inequality, we have
(a11+a21+⋯+ak1)(a1+4a2+⋯+k2ak)⩾(1+2+⋯+k)2=4k2(k+1)2
Therefore,
Hk⩽k(k+1)24(a1+4a2+⋯+k2ak)H1+H2+⋯+Hn⩽α1a1+α2a2+⋯+αnan
Thus,
where
αi=4i2(i(i+1)21+(i+1)(i+2)21+⋯+n(n+1)21),i=1,2,⋯,n
Also,
m(m+1)21<21⋅m2(m+1)22m+1=21(m21−(m+1)21)
Therefore,
αi<4i2⋅21[(i21−(i+1)21)+((i+1)21−(i+2)21)+⋯+(n21−(n+1)21)]<4i2⋅21(i21−(n+1)21)<4i2⋅2i21=2
Thus,
H1+H2+⋯+Hn⩽α1a1+α2a2+⋯+αnan<2(a1+a2+⋯+an)=2