212223

Appears in sequences

• Decimal concatenation of n, n+1, and n+2.at n=21A001703
• Summarize the previous term (digits in increasing order), starting with a(1) = 1.at n=7A005151
• Look and Say sequence: describe the previous term! (method C - initial term is 2).at n=6A023989
• Summarize the previous term in base 4 (in increasing order).at n=7A098155
• "Say what you see".at n=7A118628
• Duplicate of A001703.at n=21A127422