A219111 Numbers that eventually reach 1 under "x -> sum of 4th power of digits of x".

1, 10, 100, 1000, 10000, 11123, 11132, 11213, 11231, 11312, 11321, 12113, 12131, 12311, 13112, 13121, 13211, 21113, 21131, 21311, 23111, 31112, 31121, 31211, 32111, 44688, 44868, 44886, 46488, 46848, 46884, 48468, 48486, 48648, 48684, 48846, 48864, 64488

Offset

1,2

Links

Table of n, a(n) for n=1..38.

Example

11123 is in the sequence because 1^4 +1^4+1^4+2^4+3^4 = 100 and 1^4 + 0^4 + 0^4 = 1.
2 is not in the sequence because  2 --> 16 --> 1297 -->8979 -->19619 -->14420 -->529 -->7202 -->2433 -->434 -->593 -->7267 -->6114 -->1554 -->1507 -->3027 -->2498 -->10929 -->13139 -->6725 -->4338 -->4514 -->1138 -->4179 -->9219 -->13139 which repeats with period 7, so never reaches 1.

Mathematica

Select[Range[50000], FixedPoint[Total[IntegerDigits[#]^4]&, #, 10]==1&]

Crossrefs

Cf. A007770, A035504.

Sequence in context: A136878 A136871 A135653 * A232659 A232660 A052211

Adjacent sequences: A219108 A219109 A219110 * A219112 A219113 A219114

Keyword

nonn,base

Author

Michel Lagneau, Nov 12 2012

Status

approved