A085817 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 drop directly from 4 to 1, bypassing 2.

4, 6, 7, 9, 12, 13, 14, 15, 20, 21, 22, 23, 24, 30, 31, 36, 38, 39, 41, 44, 45, 46, 47, 52, 53, 54, 55, 56, 62, 63, 69, 70, 71, 73, 76, 77, 78, 79, 81, 86, 87, 88, 94, 95, 96, 97, 101, 102, 103, 105, 108, 109, 110, 111, 112, 118, 119, 120, 126, 127, 129, 132, 133, 134, 135, 137

Offset

1,1

Comments

No formula is known for these numbers.

Links

Table of n, a(n) for n=1..66.

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

Crossrefs

Complement of A085833.

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

Sequence in context: A367186 A345665 A343177 * A177688 A190250 A047508

Adjacent sequences: A085814 A085815 A085816 * A085818 A085819 A085820

Keyword

nonn

Author

N. J. A. Sloane, Aug 16 2003

Status

approved