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!)
 A248505 Alternating the subtraction and multiplication of two previous terms, starting with 3, 2. 1
 3, 2, -1, -2, -1, 2, 3, 6, 3, 18, 15, 270, 255, 68850, 68595, 4722765750, 4722697155, 22304192371256441250, 22304192366533744095, 497476997228678085728479670747901918750, 497476997228678085706175478381368174655 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS FORMULA For n odd a(n) = a(n-1) - a(n-2), For n even a(n) = a(n-1) * a(n-2), a(1)  = 3, a(2) = 2. EXAMPLE For n = 3, a(n) = a(2) - a(1) = 2 - 3  = -1. MATHEMATICA a248505[n_Integer] := Module[{f}, f[1] = 3; f[2] = 2; f[k_] := If[EvenQ[k], f[k - 1] * f[k - 2], f[k - 1] - f[k - 2]]; f /@ Range[n]]; a248505[21] (* Michael De Vlieger, Nov 17 2014 *) PROG (PARI) v=[3, 2]; for(n=1, 20, if(n%2, v=concat(v, v[#v]-v[#v-1])); if(!(n%2), v=concat(v, v[#v]*v[#v-1]))); v \\ Derek Orr, Oct 29 2014 CROSSREFS Cf. A248479. Sequence in context: A328928 A342468 A324534 * A254629 A096248 A079109 Adjacent sequences:  A248502 A248503 A248504 * A248506 A248507 A248508 KEYWORD sign AUTHOR Stuart E Anderson, Oct 07 2014 EXTENSIONS More terms from Colin Barker, Oct 07 2014 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 July 29 01:22 EDT 2021. Contains 346340 sequences. (Running on oeis4.)