116 words
1 minute
test02
2026-03-18

f(x)=∑i=0naixif(x)=\sum_{i=0}^{n}a_{i}x^{i}

f(x)=∑i=0nf(i)∏j=0,j≤n,j≠ix−ji−j f(x)=\sum_{i=0}^{n}f(i)\prod_{j=0,j\le n,j\neq i}\frac{x-j}{i-j}

f(x+m)=∑i=0nf(i)∏j=0,j≤n,j≠ix+m−ji−j=∑i=0nf(i)(x+m)!(x+m−n−1)!(x+m−i)i!(−1)n−i(n−i)!di=f(i)i!(−1)n−i(n−i)!ei=1m−n+iA(x)=∑i=0ndixiB(x)=∑i=0neixi[xt]A(x)B(x)=∑i=0tdiet−i=∑i=0tf(i)i!(−1)n−i(n−i)!(m−n+t−i))[xt+n]A(x)B(x)=∑i=0tdiet−i=∑i=0tf(i)i!(−1)n−i(n−i)!(m+t−i))=(x+t−n−1)!(x+t)!f(t+m)f(t+m)=(t+m)!(t+m−n−1)![xt+n]A(x)B(x)=[xt+n]A(x)B(x)∏i=t+m−nt+mi\begin{aligned} f(x+m)&=\sum_{i=0}^{n}f(i)\prod_{j=0,j\le n,j\neq i}\frac{x+m-j}{i-j}\\ &=\sum_{i=0}^{n}\frac{f(i)(x+m)!}{(x+m-n-1)!(x+m-i)i!(-1)^{n-i}(n-i)!}\\ d_{i}&=\frac{f(i)}{i!(-1)^{n-i}(n-i)!}\\ e_{i}&=\frac{1}{m-n+i}\\ A(x)&=\sum_{i=0}^{n}d_{i}x^{i}\\ B(x)&=\sum_{i=0}^{n}e_{i}x^{i}\\ [x^{t}]A(x)B(x)&=\sum_{i=0}^{t}d_{i}e_{t-i}=\sum_{i=0}^{t}\frac{f(i)}{i!(-1)^{n-i}(n-i)!(m-n+t-i))}\\ [x^{t+n}]A(x)B(x)&=\sum_{i=0}^{t}d_{i}e_{t-i}=\sum_{i=0}^{t}\frac{f(i)}{i!(-1)^{n-i}(n-i)!(m+t-i))}=\frac{(x+t-n-1)!}{(x+t)!}f(t+m)\\ f(t+m)&=\frac{(t+m)!}{(t+m-n-1)!}[x^{t+n}]A(x)B(x)=[x^{t+n}]A(x)B(x)\prod_{i=t+m-n}^{t+m}i\\ \end{aligned} g(x)=11−x[xi][g(x)]k=(k+i−1i)[xi][g−1(x)]k=(ki)(−1)i(ki)=k!i!(k−i)!=(ki−1)k−i+1i(k+i−1i)=(k+i−1)!i!(k−1)!=(k+i−2i−1)k+i−1i\begin{align} g(x)&=\frac{1}{1-x}\\ [x^{i}][g(x)]^{k}&=\binom{k+i-1}{i}\\ [x^{i}][g^{-1}(x)]^{k}&=\binom{k}{i}(-1)^{i}\\ \binom{k}{i}&=\frac{k!}{i!(k-i)!}=\binom{k}{i-1}\frac{k-i+1}{i}\\ \binom{k+i-1}{i}&=\frac{(k+i-1)!}{i!(k-1)!}=\binom{k+i-2}{i-1}\frac{k+i-1}{i} \end{align}

(ki)=k!i!(k−i)!=k(k−1)...(k−i+1)i!≡k′(k′−1)...(k′−i+1)i!=k′!i!(k′−i)!≡(k′i) \binom{k}{i}=\frac{k!}{i!(k-i)!}=\frac{k(k-1)...(k-i+1)}{i!}\equiv\frac{k'(k'-1)...(k'-i+1)}{i!}=\frac{k'!}{i!(k'-i)!}\equiv\binom{k'}{i}

(nk)=(n−1k−1)+(n−1k)g(x)=−x+1f(x)=a0+a1x+a2x2\begin{align} \binom{n}{k}=\binom{n-1}{k-1}+\binom{n-1}{k}\\ g(x)&=-x+1\\ f(x)&=a_{0}+a_{1}x+a_{2}x^{2}\\ \end{align} f(x)=∑i=0nf(x)=\sum_{i=0}^{n} ln⁡11−xV=−ln⁡(1−xV)=−∑i=1xVii=∑i=1xVii\begin{align} \ln\frac{1}{1-x^{V}}&=-\ln(1-x^{V})\\ &=-\sum_{i=1}\frac{x^{Vi}}{i}\\ &=\sum_{i=1}\frac{x^{Vi}}{i}\\ \end{align}

Bell_NumberBell\_Number

Bn+1=∑i=0n(ni)BiB_{n+1}=\sum_{i=0}^{n}\binom{n}{i}B_{i} F(x)=∑i=0Bii!xiBn+1n!=∑i=0n1(n−i)!Bii!ex⋅F(x)=F′(x)ex=F′(x)F(x)ex+c=ln⁡(F(x))F(x)=eex+cF(x)=eex−1\begin{align} F(x)&=\sum_{i=0}\frac{B_{i}}{i!}x^{i}\\ \frac{B_{n+1}}{n!}&=\sum_{i=0}^{n}\frac{1}{(n-i)!}\frac{B_{i}}{i!}\\ e^{x}\cdot F(x)&=F'(x)\\ e^{x}&=\frac{F'(x)}{F(x)}\\ e^{x}+c&=\ln(F(x))\\ F(x)&=e^{e^{x}+c}\\ F(x)&=e^{e^{x}-1} \end{align} 1011100101111010100001011000011010111001+1000011010111111100111110−76−1+6/8×2−8−7/210\begin{align} 1011 1001 0111 1010 1000 0101 1000 0110 1011 1001 + 1000 0110 1011 1111 1 00111 110 - 7 6 -1+6/8 \times 2^-8 -7/2^10 \end{align}

fif_{i}表示ii个点联通的方案数,gig_{i}表示任意一图

gn=2(n2)gn=∑i=1n(n−1i−1)fign−ign=∑i=1n(n−1)!(i−1)!(n−i)!fign−ign(n−1)!=∑i=1nfi(i−1)!gn−i(n−i)!G′(x)=F′(x)G(x)F′(x)=G′(x)G(x)F(x)=ln⁡G(x)+c\begin{align} g_{n}&=2^{\binom{n}{2}}\\ g_{n}&=\sum_{i=1}^{n}\binom{n-1}{i-1}f_{i}g_{n-i}\\ g_{n}&=\sum_{i=1}^{n}\frac{(n-1)!}{(i-1)!(n-i)!}f_{i}g_{n-i}\\ \frac{g_{n}}{(n-1)!}&=\sum_{i=1}^{n}\frac{f_{i}}{(i-1)!}\frac{g_{n-i}}{(n-i)!}\\ G'(x)&=F'(x)G(x)\\ F'(x)&=\frac{G'(x)}{G(x)}\\ F(x)&=\ln G(x)+c\\ \end{align}

\begin{align} \sum_{S\subset T}\mu(\prod_{i\in S}i)\varphi(\prod_{i\in S}i)&=0&,k=0\ \sum_{S\subset T}\mu(\prod_{i\in S}i)\varphi(\prod_{i\in S}i)&=\sum_{S\subset T}(-1)^{|S|}\prod_{i\in S}(i-1)&,k=1\ &=\sum_{S\subset T}\prod_{i\in S}(-(i-1))\ f_{p}(x)&=1-(p-1)x^{p}\ ans&=\prod_{p}f_{p}(x)|{x=1}-1\ \sum{S\subset T}\mu(\prod_{i\in S}i)\varphi(\prod_{i\in S}i)&=\sum_{S\subset T}g_{S}\prod_{i\in S}(-(i-1)) &,k=2\

\end{align}