# Finding explicit formula for recurrence relation?

What would a explicit formula for this sequence? a_k = a_(k-1)/k? The way I find explicit formula is to write out some terms but this time it's not working.. I'd appreciate your help!

• So, $$a_n=\frac{a_{n-r}}{\prod_{0\le k\le r-1}(n-k)}$$ DO you have any terminating condition like $a_1,a_0$ etc.? – lab bhattacharjee Dec 20 '13 at 16:21
• a_1=2. How did you get such a formula so quick? It looks complicated... – user48601 Dec 20 '13 at 16:22
• And k should be k>=2, sorry I forget to state in the problem – user48601 Dec 20 '13 at 16:22
• have you received your answer? – lab bhattacharjee Dec 20 '13 at 16:25

$$a_k=\frac{a_{k-1}}{k}=\frac{a_{k-2}}{k(k-1)}=......=\frac{a_1}{k!}$$