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A111403
a(n) = f(f(n+1)) - f(f(n)), where f(m) = 2^m.
3
2, 12, 240, 65280, 4294901760, 18446744069414584320, 340282366920938463444927863358058659840, 115792089237316195423570985008687907852929702298719625575994209400481361428480
OFFSET
0,1
LINKS
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
EXAMPLE
The binary representation of the first values shows what is going on:
10
1100
11110000
1111111100000000
11111111111111110000000000000000
...
MAPLE
a:= n-> (p-> p*(p-1))(2^(2^n)):
seq(a(n), n=0..7); # Alois P. Heinz, Jan 03 2018
CROSSREFS
Probably equal to A087046(n+2). Doubled A040996.
Sequence in context: A132987 A366350 A087046 * A325501 A007986 A013503
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 12 2005
EXTENSIONS
Example and cross-reference from Olivier Gérard, Jun 23 2014
STATUS
approved