A111403 a(n) = f(f(n+1)) - f(f(n)), where f(m) = 2^m.

2, 12, 240, 65280, 4294901760, 18446744069414584320, 340282366920938463444927863358058659840, 115792089237316195423570985008687907852929702298719625575994209400481361428480

Offset: 0

Author

N. J. A. Sloane, Nov 12 2005

Keywords

• nonn

Examples

			The binary representation of the first values shows what is going on:
10
1100
11110000
1111111100000000
11111111111111110000000000000000
...
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..10

Crossrefs

Probably equal to A087046(n+2). Doubled A040996.

Programs

Maple

a:= n-> (p-> p*(p-1))(2^(2^n)):
seq(a(n), n=0..7);  # Alois P. Heinz, Jan 03 2018

Formula

Conjecture: a(n) = A002716(2*n)-1. - R. J. Mathar, May 15 2007

From Alois P. Heinz, Jan 03 2018: (Start)

a(n) = 2^(2*2^n) - 2^(2^n).

a(n) = p*(p-1) with p = 2^(2^n). (End)

a(n) = A040996(n) * 2. - Tilman Piesk, Oct 04 2024

Extensions

Example and cross-reference from Olivier Gérard, Jun 23 2014