OFFSET
1,2
COMMENTS
For n > 5, a(n) >= 2p - n, where p is the largest prime less than n(n+1)/2.
FORMULA
Let A077540(n) = (k+1)(k+2)...(k+r) where k = n(n+1)/2 then a(n) = r.
EXAMPLE
a(3) = 4 as A077540(3) = 5040 = 7*8*9*10 = (6+1)(6+2)(6+3)(6+4).
PROG
(PARI) for(n=1, 100, p=1:t=n*(n+1)/2:f=1:for(k=1, n, f=f*(n+k)):for(k=1, 10^9, p=p*(t+k): if(p%f==0, print1(k", "):break)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Nov 09 2002
EXTENSIONS
Corrected and extended by Ralf Stephan, Mar 27 2003
STATUS
approved