a(1)=4; for n>=1, a(n+1) is the smallest palindromic semiprime with a(n) as a central substring.

A247483

a(1)=4; for n>=1, a(n+1) is the smallest palindromic semiprime with a(n) as a central substring.

Terms

    a(0) =4a(1) =141a(2) =41414a(3) =1414141a(4) =314141413a(5) =33141414133

External references