A094406 Smallest unhappy number that takes n steps to reach any of the unhappy cycle (4, 16, 37, 58, 89, 145, 42, 20) under iteration of sum of squares of digits map.

4, 2, 11, 15, 5, 3, 14, 45, 36, 6, 112, 269, 15999

Offset

4,1

Comments

This sequence is an analog of sequence A001273 with the unhappy numbers instead of the happy numbers.

Links

Table of n, a(n) for n=4..16.

W. Schneider, Unhappy Numbers.

Example

15 is the fourth term because: 15: 1^2 + 5^2 = 26 / 26: 2^2 + 6^2 = 40 / 40: 4^2 + 0^2 = 16 and 16 is a member of the unhappy number series (4, 16, 37, 58, 89, 145, 42, 20)

Crossrefs

Cf. A001273.

Sequence in context: A213568 A185878 A182870 * A142706 A361216 A092952

Adjacent sequences: A094403 A094404 A094405 * A094407 A094408 A094409

Keyword

nonn,base

Author

Sergio Pimentel, Apr 30 2004

Extensions

The next term, 577999999999....999999999999 (199 digits) is too large to include.

Edited by Charles R Greathouse IV, Aug 03 2010

Status

approved