A188524 In base-2 lunar arithmetic, out of all odd numbers of length n, it appears that 111..1 (with n ones) has the most lunar divisors; the sequence gives the number of lunar divisors of the runner-up.
2, 2, 4, 4, 6, 10, 16, 31, 55, 100, 185, 345, 644, 1209, 2274, 4298, 8145, 15469, 29454, 56213, 107489, 205925, 395190, 759621, 1462282, 2818799, 5440705, 10513994, 20340794, 39393580, 76368240, 148185145, 287791544, 559386196, 1088144064, 2118283567, 4126561528, 8044217224
Offset: 3
Examples
For n = 3, 4, 5 the runner-ups are 101, 1101 or 1011, 11011; thereafter they appear to be the numbers 111...101 or their reversals (see A188288).
Links
- D. Applegate, M. LeBrun and N. J. A. Sloane, Dismal Arithmetic [Note: we have now changed the name from "dismal arithmetic" to "lunar arithmetic" - the old name was too depressing]
- Index entries for sequences related to dismal (or lunar) arithmetic