A193996 Numbers that require exactly 8 iterations to determine that they are happy or not (A007770 and A031177).

4, 16, 20, 37, 42, 58, 89, 145, 78999, 79899, 79989, 79998, 87999, 89799, 89979, 89997, 97899, 97989, 97998, 98799, 98979, 98997, 99789, 99798, 99879, 99897, 99978, 99987, 378999, 379899, 379989, 379998, 387999, 389799, 389979, 389997, 389999, 397899, 397989

Offset

1,1

Comments

This sequence begins with the last 8 numbers of A039943. The number 78999 is the first happy number here.

Links

Table of n, a(n) for n=1..39.

Mathematica

f[n_] := Total[IntegerDigits[n]^2]; Select[Range[400000], Length[NestWhileList[f, #, UnsameQ, All]] - 1 == 8 &]

Crossrefs

Sequence in context: A326781 A326788 A039943 * A232400 A345763 A354712

Adjacent sequences: A193993 A193994 A193995 * A193997 A193998 A193999

Keyword

nonn,base

Author

T. D. Noe, Aug 23 2011

Status

approved