Unhappy Number

An unhappy number is a number that is not happy, i.e., a number n such that iterating this sum-of-squared-digits map starting with n never reaches the number 1.

The first few unhappy numbers are 2, 3, 4, 5, 6, 8, 9, 11, 12, 14, 15, 16, 17, 18, 20, ... (OEIS A031177).

See also

Economical Number, Evil Number, Happy Number, Lucky Number, Odious Number, Wasteful Number

Explore with Wolfram|Alpha


Sloane, N. J. A. Sequence A031177 in "The On-Line Encyclopedia of Integer Sequences."

Referenced on Wolfram|Alpha

Unhappy Number

Cite this as:

Weisstein, Eric W. "Unhappy Number." From MathWorld--A Wolfram Web Resource.

Subject classifications