A077753
a(1) = 1, a(2) = 2, a(2n) = a(2n-1)*a(2n-2), a(2n+1)= a(2n-1) + a(2n).
Original entry on oeis.org
1, 2, 3, 6, 9, 54, 63, 3402, 3465, 11787930, 11791395, 138996138862350, 138996150653745, 19319928257600060753067000750, 19319928257600199749217654495, 373259627878816004843210480238884928715510929499405871250
Offset: 1
A248505
Alternating the subtraction and multiplication of two previous terms, starting with 3, 2.
Original entry on oeis.org
3, 2, -1, -2, -1, 2, 3, 6, 3, 18, 15, 270, 255, 68850, 68595, 4722765750, 4722697155, 22304192371256441250, 22304192366533744095, 497476997228678085728479670747901918750, 497476997228678085706175478381368174655
Offset: 1
For n = 3, a(n) = a(2) - a(1) = 2 - 3 = -1.
-
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 *)
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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
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