n²⁰²⁰ + ( n+1 )²⁰²²
< ( n+1 )²⁰²² + ( n+1 )²⁰²²
= 2( n+1 )²⁰²²
≦ ( n+1 )( n+1 )²⁰²²
= ( n+1 )²⁰²³
< ( n+2 )²⁰²⁴