Engel series expansion (or "Egyptian product") for Khintchine's constant.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =9a(5) =70a(6) =117a(7) =503a(8) =648a(9) =1078a(10) =12868a(11) =41235a(12) =178650a(13) =377670a(14) =394301a(15) =546185a(16) =2600672a(17) =8729780a(18) =41318679a(19) =83367169a(20) =525961060a(21) =561571346a(22) =1556964264a(23) =1868773845a(24) =15139200289a(25) =27297789005a(26) =30324107039a(27) =56699922000