This site is supported by donations to The OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A256832 Product of first n Pell numbers Pell(1), ... , Pell(n). 6
 1, 2, 10, 120, 3480, 243600, 41168400, 16796707200, 16544756592000, 39343431175776000, 225870638380130016000, 3130567047948602021760000, 104751903991408172250111360000, 8462068308233934970708495883520000, 1650314871813323167662424409683488000000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS FORMULA a(n) = Product_{k=1..n} A000129(k). a(n) ~ c * ((1+sqrt(2))^(n*(n+1)/2) / 2^(3*n/2)), where c = A256831 = 1.1419825696677912... . - Vaclav Kotesovec, Apr 10 2015 MATHEMATICA Table[Product[Expand[((1+Sqrt[2])^k-(1-Sqrt[2])^k)/(2*Sqrt[2])], {k, 1, n}], {n, 1, 20}] FoldList[Times, LinearRecurrence[{2, 1}, {1, 2}, 20]] (* Harvey P. Dale, Oct 07 2015 *) FoldList[Times, Fibonacci[Range[20], 2]] (* or *) Table[Round[(1+Sqrt[2])^((n-1)n/2) QFactorial[n, Sqrt[8]-3]], {n, 20}] (* Vladimir Reshetnikov, Sep 15 2016 *) CROSSREFS Cf. A000129, A256831. Cf. A003266, A135407, A126772. Sequence in context: A172477 A265942 A120597 * A060690 A013038 A005321 Adjacent sequences:  A256829 A256830 A256831 * A256833 A256834 A256835 KEYWORD nonn AUTHOR Vaclav Kotesovec, Apr 10 2015 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.