A143069 Least number k such that n*k has the fewest possible ones in its binary expansion.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 5, 1, 1, 1, 1, 1, 27, 1, 1, 3, 3, 1, 41, 5, 19, 1, 565, 1, 1, 1, 1, 1, 1, 1, 7085, 27, 7, 1, 25, 1, 3, 3, 1, 3, 11, 1, 1, 41, 1, 5, 1266205, 19, 7, 1, 9, 565, 9099507, 1, 17602325, 1, 1, 1, 1, 1, 128207979, 1, 1, 1, 119, 1, 1, 7085, 1, 27, 5, 7, 13

Offset: 1

Author

T. D. Noe, Jul 22 2008

Keywords

• nonn

Comments

a(n)=1 indicates that n is a sturdy number (A125121); that is, no multiple of n has fewer ones than the binary expansion of n. A086342(n) gives the least possible number of ones in the binary expansion of a multiple of n. Compare with A143073.

Links

• T. D. Noe, Table of n, a(n) for n=1..1000
• Trevor Clokie et al., Computational Aspects of Sturdy and Flimsy Numbers, arxiv preprint arXiv:2002.02731 [cs.DS], February 7 2020.