OFFSET
1,1
COMMENTS
A006577 is the number of halving and tripling steps to reach 1 in '3x+1' problem.
a(n) = 0 for n = 3, 4, 11, 14, 17, 18, 19, 20, 21, 23, 47, 54, 55, 73, ...
MAPLE
lst:={ }:C:= proc(n) a := 0 ; x := n ; while x > 1 do if type(x, 'even') then x := x/2:a:=a+1: else x := 3*x+1 ; a := a+1 ; end if; end do; a ; end proc:
for n from 1 to 73 do: ii:=0:for k from 2 to 100000 while(ii=0) do:z:=n+k : if C(z)=C(n)+C(k) then ii:=1: printf ( "%d %d \n", n, k):else fi:od: if ii=0 then printf ( "%d %d \n", n, 0):else fi:od:
CROSSREFS
KEYWORD
nonn
AUTHOR
Michel Lagneau, Feb 25 2013
STATUS
approved