This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A216151 a(n+1) = prod(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 Alois P. Heinz, Table of n, a(n) for n = 1..10 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: A181036 A222854 A059088 * A057771 A056164 A156500 Adjacent sequences:  A216148 A216149 A216150 * A216152 A216153 A216154 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 | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified October 22 21:09 EDT 2018. Contains 316505 sequences. (Running on oeis4.)