415416

Appears in sequences

• Numbers that can be expressed as the sum of the first j integer numbers or the first k nonprime numbers, with j and k >=1.at n=4A154588
• a(1) = 1, a(n) = least proper multiple of a(n-1) which is a concatenation of two or more successive numbers.at n=3A225796
• Triangular numbers obtained as the concatenation of n and n+1.at n=6A226788