OFFSET
0,4
FORMULA
a(n) <= binomial(A000009(n)+n-1,n) with equality only for n < 11.
EXAMPLE
a(5) = 21: 55555, 555532, 555541, 5553322, 5554321, 5554411, 55333222, 55433221, 55443211, 55444111, 533332222, 543332221, 544332211, 544432111, 544441111, 3333322222, 4333322221, 4433322211, 4443322111, 4444321111, 4444411111.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Alois P. Heinz, Apr 05 2017
STATUS
approved