NISHIO Hirokazu[Translate]
下固定の二項係数→重複組合せ
\binom{A+i}{A} = \binom{A+i}{i} = H^{A+1}_i

\binom{A+i}{A} = H_A^{i+1}
後者も成り立つが、前者の方が固定の枠に可変のボールを置く形なので重複組合せの畳み込みは自然な形になりそう



"Engineer's way of creating knowledge" the English version of my book is now available on [Engineer's way of creating knowledge]

(C)NISHIO Hirokazu / Converted from [Scrapbox] at [Edit]