1,2

N. J. A. Sloane et al., Notes on the attempt to find a(8)

4 -> 2, prime, so a(4) = 2.

6 -> 2,3 -> 23, prime, so a(6) = 23.

8 -> 2.4 -> 24 -> 2.3.4.6.8.12 -> 2346812 -> 2.4.13.26.52.45131.90262.180524.586703.1173406 -> 2413265245131902621805245867031173406 -> ? (see link for the continuation)

9 -> 3, prime, so a(9) = 3.

21 -> 3,7 -> 37, prime, so a(21) = 37.

Cf. A120712, A120713, A037274, A130139-A130142. A130139 is a bisection.

Sequence in context: A010242 A086507 A133568 this_sequence A084318 A084317 A037279

Adjacent sequences: A120713 A120714 A120715 this_sequence A120717 A120718 A120719

nonn,base,more,hard

N. J. A. Sloane (njas(AT)research.att.com), Jul 19 2007

a(8) is currently unknown.