The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A133376 a(n) = (...((2^3)^4)^...)^n. 1
2, 8, 4096, 1152921504606846976, 2348542582773833227889480596789337027375682548908319870707290971532209025114608443463698998384768703031934976 (list; graph; refs; listen; history; text; internal format)
OFFSET
2,1
COMMENTS
Another kind of exponential factorial.
See cross-references for other possible definitions of exponential factorials.
Some other terms of the sequence can be computed, but they are quite large and it wouldn't be very convenient to display them.
The next term has 759 digits. - Harvey P. Dale, Oct 22 2019
LINKS
FORMULA
a(n) = 2^(n!/2) for n >= 2. - Karl W. Heuer, Nov 25 2014
EXAMPLE
a(4) = 4096, as (2^3)^4 = 4096.
MAPLE
expfact:= proc(n::integer) local i, res; res:=2; for i from 3 to n do res:=(res)^i od; res end proc; seq(expfact(n), n=2..7);
# second Maple program:
a:= proc(n) option remember;
`if`(n<3, n, a(n-1)^n)
end:
seq(a(n), n=2..6); # Alois P. Heinz, Jan 17 2024
MATHEMATICA
nxt[{n_, a_}]:={n+1, a^(n+1)}; NestList[nxt, {2, 2}, 4][[All, 2]] (* Harvey P. Dale, Oct 22 2019 *)
CROSSREFS
Sequence in context: A174736 A324567 A135238 * A179056 A160814 A038582
KEYWORD
nonn
AUTHOR
Pierre Karpman (pierre.karpman(AT)laposte.net), Oct 28 2007
STATUS
approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 14 21:34 EDT 2024. Contains 373401 sequences. (Running on oeis4.)