Let N = 1357911131517192123252729313335373941434547495153555759616365676971..., the concatenation of the odd numbers. a(n) is the n-digit number formed from the digits of N starting from the {n(n-1)/2 +1}th digit. Omit any leading zeros.

A066553

Let N = 1357911131517192123252729313335373941434547495153555759616365676971..., the concatenation of the odd numbers. a(n) is the n-digit number formed from the digits of N starting from the {n(n-1)/2 +1}th digit. Omit any leading zeros.