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%I #20 Sep 08 2022 08:45:09
%S 1,1,2,3,6,15,50,235,1498,12592,135431,1806803,29135476,555971158,
%T 12336554787,313733168860,9034347750986,291579097035392,
%U 10455240487002922,413371595329570610
%N A 2nd-order recursion: a(1)=a(2)=1; a(n) = prime(a(n-1)) + primepi(a(n-2)) = A000040(a(n-1)) + A000720(a(n-2)).
%t a[n_]:= a[n]= If[n<4, Fibonacci[n], Prime[a[n-1]] + PrimePi[a[n-2]]]; Table[a[n], {n,1,17}] (* modified by _G. C. Greubel_, Aug 31 2019 *)
%o (Magma) a:= func< n | n lt 4 select Fibonacci(n) else NthPrime(Self(n-1)) + #PrimesUpTo(Self(n-2)) >;
%o [a(n): n in [1..14]]; // _G. C. Greubel_, Aug 31 2019
%Y Cf. A069103, A082095.
%K nonn,more
%O 1,3
%A _Labos Elemer_, Apr 11 2003
%E a(17) from _G. C. Greubel_, Aug 31 2019
%E a(18)-a(20) from _Chai Wah Wu_, Sep 18 2019
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