OFFSET
1,1
COMMENTS
Numbers n such that A258825(n) > 0.
EXAMPLE
For n = 5, the Collatz function does the following: 5 -> 8 -> 4 -> 2 -> 1. Here, for k = 1, 2, 3, 4, applying k iterations to 5 does not yield k. So 5 is not a member of this sequence.
For n = 6, the Collatz function does the following: 6 -> 3 -> 5 -> 8 -> 4 -> 2 -> 1. After the 4th iteration, you arrive at 4. So 6 is a member of this sequence.
PROG
(PARI) Tvect(n)=v=[n]; while(n!=1, if(n%2, k=(3*n+1)/2; v=concat(v, k); n=k); if(!(n%2), k=n/2; v=concat(v, k); n=k)); v
n=1; while(n<10^3, d=Tvect(n); c=0; for(i=1, #d, if(d[i]==i-1, print1(n, ", "); break)); n++)
CROSSREFS
KEYWORD
nonn
AUTHOR
Derek Orr, Jun 11 2015
STATUS
approved