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!)
A216151 a(n+1) = (Product_{k=1..n} a(k)) * Sum_{k=1..n} a(k), a(1)=1, a(2)=2. 2
1, 2, 6, 108, 151632, 29820965660928, 174758887882787264327879044178706432 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
Conjecture: a(n) > A057194(n) for all n > 1.
a(n) is about x^y^n with y = phi^2 = 2.61803398874... and x around 1.101029823705009804368. - Charles R Greathouse IV, Sep 12 2012
LINKS
EXAMPLE
a(4) = 108 = (6+2+1)*(6*2*1).
MAPLE
a:= proc(n) a(n):= `if`(n<3, n,
mul(a(k), k=1..n-1) * add(a(k), k=1..n-1))
end:
seq (a(n), n=1..10); # Alois P. Heinz, Sep 12 2012
MATHEMATICA
t = {1, 2}; Do[AppendTo[t, (Plus @@ t) (Times @@ t)], {5}]; t (* T. D. Noe, Sep 04 2012 *)
PROG
(PARI) v=vector(10, i, i); for(i=3, #v, v[i] = prod(j=1, i-1, v[j])*sum(j=1, i-1, v[j])); v \\ Charles R Greathouse IV, Sep 12 2012
(Haskell)
a216151 n = a216151_list !! (n-1)
a216151_list = 1 : 2 : f 2 3 where
f u v = w : f (u * w) (v + w) where w = u * v
-- Reinhard Zumkeller, Mar 20 2014
CROSSREFS
Cf. A057194.
Sequence in context: A222854 A351780 A059088 * A057771 A056164 A156500
KEYWORD
nonn
AUTHOR
Jon Perry, Sep 02 2012
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 April 21 16:18 EDT 2024. Contains 371874 sequences. (Running on oeis4.)