A085703 a(1)=4, then least semiprime > a(n-1) such that when all in the sequence are concatenated together they form a prime.

4, 21, 39, 49, 93, 161, 183, 201, 411, 543, 1003, 1043, 1387, 1389, 1527, 1589, 2509, 2519, 2559, 2881, 4143, 4613, 4821, 5251, 6821, 7123, 7671, 7679, 8373, 9993, 11463, 13201, 13349, 13647, 14349, 17617, 17753, 18931, 19253

Offset

1,1

Links

Table of n, a(n) for n=1..39.

Example

a(3)=39 because it is a semiprime and 42139 is prime.

Crossrefs

Sequence in context: A188219 A280091 A086474 * A063122 A110737 A273417

Adjacent sequences: A085700 A085701 A085702 * A085704 A085705 A085706

Keyword

nonn,base

Author

Jason Earls and Amarnath Murthy, Jul 18 2003

Status

approved