0,1

The product of a pair of consecutive refactorable numbers is itself refactorable.

S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.

S. Colton, HR - Automatic Theory Formation in Pure Mathematics

8 is refactorable because tau(8)=4 and 4 divides 8. 9 is refactorable because tau(9)=3 and 3 divides 9. So 8*9 = 72 is in the sequence.

A033950.

Sequence in context: A062082 A067689 A079478 this_sequence A041647 A083018 A062552

Adjacent sequences: A036896 A036897 A036898 this_sequence A036900 A036901 A036902

nonn

Simon Colton (simonco(AT)cs.york.ac.uk)