1,2

Each term is odd.

Can it be proved that there always is a positive multiple of each a(n-1) that has exactly n binary 1's? Or is the {a(k)} sequence finite?

a(10) <= 1 + 2^100 + 2^236 + 2^238 + 2^341 + 2^542 + 2^566 + 2^568 + 2^674 + 2^723. [From Max Alekseyev, Oct 12 2008]

Table of n, a(n) for n=1..9.

Sequence in context: A134057 A128281 A034268 * A054147 A233582 A043012

Adjacent sequences: A140448 A140449 A140450 * A140452 A140453 A140454

base,more,nonn

Leroy Quet, Jul 21 2008

First 8 terms calculated by R. J. Mathar and Jack Brennen.

a(9) from Max Alekseyev, Jul 22 2008

approved