_N. J. A. Sloane (njas(AT)research.att.com), _, Aug 18 2009

<a href="/Sindx_index/K.html#Kaprekar_map">Index entries for the Kaprekar map</a>

<a href="/Sindx_index/Ra.html#RATS">Index entries for RATS sequences</a>

<a href="/Sindx_K.html#Kaprekar_map">Index entries for the Kaprekar map</a>

<a href="/Sindx_Ra.html#RATS">Index entries for RATS sequences</a>

nonn,base,new

a(1) = 8127; thereafter a(n) = (a(n-1) with digits sorted into descending order) - (a(n-1) with digits sorted into ascending order) (see the Kaprekar map, A151949).

8127, 7443, 3996, 6264, 4176, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174, 6174

1,1

Similar in spirit to the RATS (Reverse, Add Then Sort) sequences.

Converges to the fixed point 6174. For the list of fixed points see A099009.

The initial value 1001 is the smallest number that converges to 6174 - see A151967.

John Tierney, <a href="http://nytimes.com/tierneylab">"TierneyLab" column, New York Times, Section C, Aug 18 2009</a>

<a href="Sindx_K.html#Kaprekar_map">Index entries for the Kaprekar map</a>

<a href="Sindx_Ra.html#RATS">Index entries for RATS sequences</a>

Cf. A099009, A151947, A151949, A151951, A151955, A151956, A151967. A151968.

nonn,base

N. J. A. Sloane (njas(AT)research.att.com), Aug 18 2009

approved