OFFSET
1,3
COMMENTS
Union of rows of triangle A231330. - Reinhard Zumkeller, Nov 08 2013
LINKS
Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
PROG
(Haskell)
a230872 n = a230872_list !! (n-1)
a230872_list = f [] a231330_tabf where
f ws (xs:xss) = us ++ f (merge vs xs) xss where
(us, vs) = span (< head xs) ws
merge us [] = us
merge [] vs = vs
merge us'@(u:us) vs'@(v:vs)
| u < v = u : merge us vs'
| u > v = v : merge us' vs
| otherwise = u : merge us vs
-- Reinhard Zumkeller, Nov 08 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 07 2013
STATUS
approved