A083992 - OEIS

A083992

a(1) = 1; then the smallest number such that both the forward and reverse n-th partial concatenation is a prime for n > 1. (Reverse concatenation is taken term-wise and not digit-wise.)

%I #7 May 06 2018 00:43:53

%S 1,1,3,11,13,47,67,213,99,753,861,143,2187,249,193,2957,14553,1557,

%T 2359,8669,1491,1003,12131,583,2643,3857,5631,999,9693,10231,1451,

%U 16861,6321,14567,21649,7563,40983,123,12579,57927,4257,6777,359,3679,1191,10139

%N a(1) = 1; then the smallest number such that both the forward and reverse n-th partial concatenation is a prime for n > 1. (Reverse concatenation is taken term-wise and not digit-wise.)

%e Both 1131113 and 1311311 are primes as a forward and reverse concatenation of the first five terms (1,1,3,11,13).

%Y Cf. A083993, A083994.

%K base,hard,nonn

%O 0,3

%A _Amarnath Murthy_, May 23 2003

%E More terms from _Ray Chandler_, Aug 03 2003