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A151957 Iterate the Kaprekar map of A151949 starting at the n-digit number 100...02; sequence gives the lowest number in the resulting cycle. 5
0, 495, 6174, 62964, 420876, 7509843, 64308654, 753098643, 6431088654, 86420987532, 643330866654, 8764209875322, 64333308666654, 885432098765412, 6543331088666544, 88543320987665412, 975533110888664421 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,2
LINKS
Joseph Myers, Table of n, a(n) for n=2..1000 [From Joseph Myers, Aug 21 2009]
MAPLE
A151949 := proc(n)
local tup;
tup := sort(convert(n, base, 10)) ;
add( (op(i, tup)-op(-i, tup)) *10^(i-1), i=1..nops(tup)) :
end:
A151957 := proc(n)
local tra, x ;
x := 10^(n-1)+2 ;
tra := [x] ;
while true do
x := A151949(x) ;
if member(x, tra, 'l') then
op(l..nops(tra), tra) ;
RETURN(min(%)) ;
fi;
tra := [op(tra), x] :
od:
end:
seq(A151957(n), n=2..60) ;
# R. J. Mathar, Aug 20 2009
MATHEMATICA
To find the first 20 terms of the trajectory of 10002, for instance:
f[n_]:=Module[{idn=IntegerDigits[n], idns}, idns=Sort[idn]; Abs[FromDigits[ idns]-FromDigits[Reverse[idns]]]]
NestList[f, 10002, 20]
CROSSREFS
See A151958 for the length of the cycles. Cf. A151949, A151955 (the trajectory of 102), A151956 (the trajectory of 1002).
See also A151967, A151968.
Sequence in context: A164716 A164718 A151965 * A099009 A055160 A055157
KEYWORD
nonn,base
AUTHOR
Harvey P. Dale and N. J. A. Sloane, Aug 18 2009, Aug 19 2009
EXTENSIONS
Extended by R. J. Mathar and Joseph Myers, Aug 20 2009
STATUS
approved

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Last modified March 19 03:21 EDT 2024. Contains 370952 sequences. (Running on oeis4.)