Concatenate prevprime(n), n, and nextprime(n).

Terms

a(0) =235a(1) =345a(2) =357a(3) =567a(4) =5711a(5) =7811a(6) =7911a(7) =71011a(8) =71113a(9) =111213a(10) =111317a(11) =131417a(12) =131517a(13) =131617a(14) =131719a(15) =171819a(16) =171923a(17) =192023a(18) =192123a(19) =192223a(20) =192329a(21) =232429a(22) =232529a(23) =232629a(24) =232729a(25) =232829a(26) =232931a(27) =293031a(28) =293137a(29) =313237