A085833 Start at (2n+1)/4 and iterate the map x -> x*ceiling(x); sequence gives values of n for which the denominators in the orbit go from 4 to 2, instead of dropping directly to 1.

2, 3, 5, 8, 10, 11, 16, 17, 18, 19, 25, 26, 27, 28, 29, 32, 33, 34, 35, 37, 40, 42, 43, 48, 49, 50, 51, 57, 58, 59, 60, 61, 64, 65, 66, 67, 68, 72, 74, 75, 80, 82, 83, 84, 85, 89, 90, 91, 92, 93, 98, 99, 100, 104, 106, 107, 113, 114, 115, 116, 117, 121, 122, 123, 124, 125, 128, 130

Offset

1,1

Comments

No formula is known for these numbers.

Links

Table of n, a(n) for n=1..68.

J. C. Lagarias and N. J. A. Sloane, Approximate squaring (pdf, ps), Experimental Math., 13 (2004), 113-128.

Crossrefs

Complement of A085817.

A073341 gives number of steps until reach an integer. Cf. A085785.

Sequence in context: A326379 A099107 A261255 * A066896 A369064 A277625

Adjacent sequences: A085830 A085831 A085832 * A085834 A085835 A085836

Keyword

nonn

Author

N. J. A. Sloane, Aug 16 2003

Status

approved