OFFSET
1,2
COMMENTS
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
Reinhard Zumkeller, First 10000 products of any two terms of A237424
EXAMPLE
PROG
(Haskell)
import Data.Set (empty, fromList, deleteFindMin, union)
import qualified Data.Set as Set (null)
a254143 n = a254143_list !! (n-1)
a254143_list = f a237424_list [] empty where
f xs'@(x:xs) zs s
| Set.null s || x < y = f xs zs' (union s $ fromList $ map (* x) zs')
| otherwise = y : f xs' zs s'
where zs' = x : zs
(y, s') = deleteFindMin s
(PARI) listA237424(lim)=my(v=List(), a, t); while(1, for(b=0, a, t=(10^a+10^b+1)/3; if(t>lim, return(Set(v))); listput(v, t)); a++)
list(lim)=my(v=List(), u=listA237424(lim), t); for(i=1, #u, for(j=1, i, t=u[i]*u[j]; if(t>lim, break); listput(v, t))); Set(v) \\ Charles R Greathouse IV, May 13 2015
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jan 28 2015
STATUS
approved