A175985 a(1) = 1, for n >= 2: a(n) = (a(n-1)+1)^(n-1) - 1.

1, 1, 3, 63, 16777215, 1329227995784915872903807060280344575

Offset

1,3

Comments

The next term (a(7)) has 217 digits.

Links

Table of n, a(n) for n=1..6.

Formula

a(n+1) = 2^A000142(n) - 1; A000142 = factorial numbers.

Example

For n = 4: a(4) = (3+1)^3 - 1 = 63.

Prog

(PARI) a(n)=if(n<=1, 1, (a(n-1)+1)^(n-1)-1); /* Joerg Arndt, Jun 10 2011 */

Crossrefs

Sequence in context: A156904 A193100 A053857 * A037108 A249097 A092901

Adjacent sequences: A175982 A175983 A175984 * A175986 A175987 A175988

Keyword

nonn,easy

Author

Jaroslav Krizek, Nov 03 2010

Status

approved