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A284374 a(1) = a(2) = 1; a(n) is the largest prime <= (a(n-a(n-1)) + a(n-a(n-2))) for n > 2.

%I A284374 #20 Mar 30 2017 01:14:26
%S A284374 1,1,2,3,3,3,5,5,5,5,5,7,7,7,7,7,7,7,13,11,7,11,13,11,13,13,13,13,13,
%T A284374 13,13,23,13,11,19,19,13,23,19,13,23,23,19,19,23,23,19,23,23,23,23,23,
%U A284374 23,23,43,19,29,31,23,23,43,31,31,23,31,37,31,23,43,31,23,43,31
%N A284374 a(1) = a(2) = 1; a(n) is the largest prime <= (a(n-a(n-1)) + a(n-a(n-2))) for n > 2.
%H A284374 Altug Alkan, <a href="/A284374/b284374.txt">Table of n, a(n) for n = 1..10000</a>
%H A284374 Altug Alkan, <a href="/A284374/a284374.png">Alternative scatterplot of A284374</a>
%H A284374 Altug Alkan, <a href="/A284374/a284374_1.png">Alternative graph of A284374</a>
%F A284374 a(1) = a(2) = 1; a(n) = A007917(a(n-a(n-1)) + a(n-a(n-2))) for n > 2.
%e A284374 a(4) = 3 because a(4 - a(3)) + a(4 - a(2)) = a(2) + a(3) = 1 + 2 = 3 and A007917(3) = 3.
%t A284374 a[1] = a[2] = 1; a[n_] := a[n] = Prime@ PrimePi[a[n - a[n - 1]] + a[n - a[n - 2]]]; Array[a, 73] (* _Michael De Vlieger_, Mar 25 2017 *)
%o A284374 (PARI) a=vector(1000); a[1]=a[2]=1; for(n=3, #a, a[n] = precprime(a[n-a[n-1]]+a[n-a[n-2]])); a
%Y A284374 Cf. A005185, A007917, A284383, A284397.
%K A284374 nonn
%O A284374 1,3
%A A284374 _Altug Alkan_, Mar 25 2017