[ exp(1/7)*n! ].

Terms

a(0) =1a(1) =2a(2) =6a(3) =27a(4) =138a(5) =830a(6) =5813a(7) =46511a(8) =418605a(9) =4186056a(10) =46046623a(11) =552559478a(12) =7183273217a(13) =100565825043