11 人解决，12 人已尝试。
29 份提交通过，共有 49 份提交。
4.6 EMB 奖励。
单点时限: 2.0 sec
内存限制: 256 MB
The rhyme scheme for a poem (or stanza of a longer poem) tells which lines of the poem rhyme with which other lines. For example, a limerick such as
If computers that you build are quantum
Then spies of all factions will want ‘em
Our codes will all fail
And they’ll read our email
‘Til we’ve crypto that’s quantum and daunt ‘em
Has a rhyme scheme of aabba, indicating that the first, second and fifth lines rhyme and the third and fourth lines rhyme.
For a poem or stanza of four lines, there are 15 possible rhyme schemes: aaaa, aaab, aaba, aabb, aabc, abaa, abab, abac, abba, abbb, abbc, abca, abcb, abcc, and abcd.
Write a program to compute the number of rhyme schemes for a poem or stanza of $N$ lines where $N$ is an input value.
Input will consist of a sequence of integers $N$ ($N \le 50$), one per line, ending with a $0$ (zero) to indicate the end of the data. $N$ is the number of lines in a poem.
For each input integer $N$, your program should output the value of $N$, followed by a space, followed by the number of rhyme schemes for a poem with $N$ lines as a decimal integer with at least $12$ correct significant digits (use double precision floating point for your computations).
1 2 3 4 20 30 10 0
1 1 2 2 3 5 4 15 20 51724158235372 30 846749014511809120000000 10 115975
11 人解决，12 人已尝试。
29 份提交通过，共有 49 份提交。
4.6 EMB 奖励。