A235055 The greedy sequence of real numbers at least 1 that do not contain any 4-term geometric progressions with integer ratio

1, 8, 16, 48, 200, 216, 288, 1200, 1296, 1400, 1512, 1600, 1728, 1800, 1944, 2000, 62400, 63936, 73800, 74088, 75600, 79704, 80688, 81648, 88000, 499200, 511488, 590400, 592704, 604800, 637632, 645504, 653184, 704000, 998400

Offset

1,2

Comments

The union of the half-open intervals [a(2i-1),a(2i)) is the greedy set of real numbers at least 1 that does not contain any subset of the form {a, ar, ar^2, ar^3} with r an integer.

Links

Table of n, a(n) for n=1..35.

M. B. Nathanson, K. O'Bryant, A problem of Rankin on sets without geometric progressions, arXiv preprint arXiv:1408.2880, 2014

Crossrefs

A235054 through A235060 give the greedy sets avoiding k-term geometric progressions for 3 <= k <= 9.

Sequence in context: A214204 A335771 A159038 * A209997 A212764 A133581

Adjacent sequences: A235052 A235053 A235054 * A235056 A235057 A235058

Keyword

nonn

Author

Kevin O'Bryant, Jan 03 2014

Status

approved