The equation should be
a n + 2 = − 20 n ( n + 1 ) a n + 1 + n ( n − 1 ) a n + a n 101 ( n + 2 ) ( n + 1 ) {\displaystyle a_{n+2}=-{\frac {20n(n+1)a_{n+1}+n(n-1)a_{n}+a_{n}}{101(n+2)(n+1)}}}
Return to errata.
