The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A142471 a(0) = a(1) = 0; thereafter a(n) = a(n-1)*a(n-2) + 2. 2
 0, 0, 2, 2, 6, 14, 86, 1206, 103718, 125083910, 12973452977382, 1622770224612082123622, 21052933202100473722674133293917606, 34164073141115747076263787631563122725393126176374288934 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 LINKS Vincenzo Librandi, Table of n, a(n) for n = 0..19 A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, Fib. Quart., 11 (1973), 429-437. FORMULA a(n) ~ c^(phi^n), where c = 1.278178162398588325773605473403497130099080978627235683548955136178125... and phi = A001622 = (1+sqrt(5))/2 is the golden ratio. - Vaclav Kotesovec, May 21 2015 MATHEMATICA a[0] = a[1] = 0; a[n_] := a[n-1] a[n-2] + 2; Table[a[n], {n, 0, 15}] (* T. D. Noe, Nov 14 2011 *) PROG (MAGMA) I:=[0, 0]; [n le 2 select I[n] else Self(n-1)*Self(n-2)+2: n in [1..15]]; // Vincenzo Librandi, Nov 14 2011 CROSSREFS Cf. A007660, A000058, A143684. Sequence in context: A014431 A201687 A259810 * A323233 A071208 A231536 Adjacent sequences:  A142468 A142469 A142470 * A142472 A142473 A142474 KEYWORD nonn AUTHOR N. J. A. Sloane, based on email from Carla J. Garner-Bennett, Nov 13 2008 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
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 8 19:12 EDT 2020. Contains 336298 sequences. (Running on oeis4.)