A068533 a(n) = (11^(2^n)-1)/2^(n+2)/15.

1, 61, 446581, 47864301941221, 1099675872153778794555007944901, 1160915542845287082257685451398396234242229540362376748831753861, 2587631803429953767431812922335511171298614788064511166728057883038770884444505265048062877435638536484571643805442456022573810181

Offset: 1

Author

Benoit Cloitre, Mar 22 2002

Keywords

• easy
• nonn