>>331
(引用開始)
google：
series Σ _{k＝0,1,…,+∞}(1/(k!＋1)) irrational number proof
AIモード 回答
The question of whether the series Σ _{k＝0,1,…,+∞}(1/(k!＋1)) is irrational appears to be an open problem in mathematics. No established proof has been found to confirm its irrationality, though it is strongly suspected to be an irrational number.
以下略
(引用終り)

”irrational appears to be an open problem in mathematics. No established proof has been found to confirm its irrationality”
ね
本当に open problem ＝未解決問題
かどうか 裏付けがないが
open problem ＝未解決問題 ならば
フェルマーの最終定理の次の
素人わかりする open problem ＝未解決問題 かも・・　（＾＾