209961

Appears in sequences

• Concatenations C1 and C2 and C3 are all prime (see the comment lines).at n=33A034817
• a(0)=0, a(1)=1, a(n) = min{5 a(k) + (5^(n-k)-1)/4, k=0..(n-1)} for n>=2.at n=29A259669