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A219111 Numbers that eventually reach 1 under "x -> sum of 4th power of digits of x". 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified February 20 06:26 EST 2019. Contains 320332 sequences. (Running on oeis4.)