OFFSET
1,1
COMMENTS
The NAME suggests that this is an erroneous version of A340585 (which includes 25, for example), but the Haskell implementation indicates that the true definition is more complicated. - R. J. Mathar, Jan 13 2021
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
FORMULA
A052409(a(n)) mod 3 > 0.
PROG
(Haskell)
import Data.Map (singleton, findMin, deleteMin, insert)
a239870 n = a239870_list !! (n-1)
a239870_list = f 9 (3, 2) (singleton 4 (2, 2)) where
f zz (bz, ez) m
| xx < zz = if ex `mod` 3 > 0
then xx : f zz (bz, ez+1) (insert (bx*xx) (bx, ex+1) $ deleteMin m)
else f zz (bz, ez+1) (insert (bx*xx) (bx, ex+1) $ deleteMin m)
| xx > zz = if ez `mod` 3 > 0
then zz : f (zz+2*bz+1) (bz+1, 2) (insert (bz*zz) (bz, 3) m)
else f (zz+2*bz+1) (bz+1, 2) (insert (bz*zz) (bz, 3) m)
| otherwise = f (zz+2*bz+1) (bz+1, 2) m
where (xx, (bx, ex)) = findMin m -- bx ^ ex == xx
CROSSREFS
KEYWORD
nonn,obsc
AUTHOR
Reinhard Zumkeller, Mar 28 2014
STATUS
approved