例如:A(x)=1+x+5*x^2/2!+67*x^3/3!+1937*x^4/4!+98791*x^5/5!+。。。
哪里
初始术语说明。
如果我们形成一个系数数组x^k/k!在A(x)^n中,n>=0,如下所示:
A^0:[1]、0、0、0,0、0,0、0。。。;
A^1:[1,1],5,671937,98791,7744549,857382695。。。;
A^2:[1,2,12],164,4560,223652,170549201853019716。。。;
A^3:[1,3,21,297],8049380853282733008400909。。。;
A^4:[1,4,32,472,12608],577864,41657008,4348646600。。。;
A^5:[1,5,45,69518465,823475],57747565,5903103995。。。;
A^6:[1,6,60,972,25872,1127916,77020344],7706019180。。。;
A^7:[1,7,77,1309,35105,15029977,100075045,9797289761]。。。
然后我们可以说明,在A(x)^n(如上括号所示)中,x^k,k=0..n的系数之和如何等于(n+1)^n:
1^0 = 1;
2^1 = 1 + 1 = 2;
3^2 = 1 + 2 + 12/2! = 9;
4^3 = 1 + 3 + 21/2! + 297/3! = 64;
5^4 = 1 + 4 + 32/2! + 472/3! + 12608/4! = 625;
6^5 = 1 + 5 + 45/2! + 695/3! + 18465/4! + 823475/5! = 7776;
7^6 = 1 + 6 + 60/2! + 972/3! + 25872/4! + 1127916/5! + 77020344/6! = 117649; ...
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