A075121 First integer reached when starting with n/floor(sqrt(n)) and iterating the map x -> x*ceiling(x) A075120(n) times, or -1 if no integer is ever reached.

1, 2, 3, 2, 60, 3, 14, 4, 3, 1484710602474311520, 220, 4, 227370, 560, 5, 4, 218790, 268065, 570, 5, 1008, 33, 1458660, 6, 5

Offset

1,2

Comments

a(26) = 9.20120538...*10^191 is too large to be included in Data. - Jinyuan Wang, Jan 15 2022

Links

Jinyuan Wang, Table of n, a(n) for n = 1..50

Example

n=13: after A075120(13)=3 steps 13/floor(sqrt(13)) = 13/3 -> 65/3 -> 1430/3 -> 227370, therefore a(13)=227370.

Crossrefs

Cf. A075103, A075108, A075120.

Sequence in context: A178134 A369190 A291489 * A075108 A364139 A265590

Adjacent sequences: A075118 A075119 A075120 * A075122 A075123 A075124

Keyword

nonn

Author

Reinhard Zumkeller, Sep 03 2002

Status

approved