Simple Dynamic Programming Approach,  Math wasn't mathing for me
PICK n letters where we must have 1 l , 2 e and 1 t at any random position\n# Code\n\nclass Solution:\n    def stringCount(self, n: int) -> int:\n        if(n<4
PICK n letters where we must have 1 l , 2 e and 1 t at any random position\n# Code\n```\nclass Solution:\n    def stringCount(self, n: int) -> int:\n        if(n<4):\n            return 0\n        @cache\n        def do(po,l,e,t):\n            if(po==0):\n                return 1\n            k=0\n            if(l>0):\n                k+=do(po-1,l-1,e,t)\n            if(e>0):\n                k+=do(po-1,l,e-1,t)\n            if(t>0):\n                k+=do(po-1,l,e,t-1)\n            if(po>l+e+t):\n                rem=23\n                if(l==0):\n                    rem+=1\n                if(e==0):\n                    rem+=1\n                if(t==0):\n                    rem+=1\n                k+=rem*do(po-1,l,e,t)\n            return k%1000000007\n        return do(n,1,2,1)\n        \n```
['Dynamic Programming', 'Python3']