anlimnan{an}
C or D
limn(1)nan{(1)nan}
C or D
an
AC, CC, or D
(1)nan
AC, CC, or D
4n!2nDDNEDDD
(n+2)3nn!0C0CACAC
4n(3n)n0C0CACAC
1(2n+1)!0C0CACAC