int tan_zigzag_number(int count)

{

int ft = 1;

int *st = (int *)malloc(sizeof(int) * count);

for(int i = 0; i < count; i++)

st[i] = 0;

for(int i = 1; i <= (count + 1); i++)

ft *= i, st[i] = ft;

for(int i = 1; i <= (count + 1); i++)

for(int k = 1; k <= (count - i); k++)

{

st[k] *= k;

if(k > 1)

st[k] += st[k - 1];

}

ft = *st;

free(st);

return ft;

}


탄젠트 갈지자숫자라는 거거든?


http://en.wikipedia.org/wiki/Alternating_permutation

http://www.cryptographic.co.uk/diagrams/tantriangle.png