101211

Appears in sequences

• Concatenations C1 and C2 and C3 and C4 are all prime (see the comment lines).at n=22A034819
• Number of length 6+3 0..n arrays with some disjoint pairs in every consecutive four terms having the same sum.at n=9A247538
• a(n) is the concatenation of 3n-2, 3n and 3n-1.at n=3A248555
• a(0) = a(1) = 1; a(n+2) = Sum_{k=0..n} (binomial(n,k) mod 2) * a(k).at n=37A331520