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%I #11 Nov 14 2020 09:46:21
%S 1,4,28,477,15054,716619,46386636,3829544473,386956394842,
%T 46498297487679,6503866348955704,1041432998153210277,
%U 188367392877258840974
%N a(0) = 1; for n > 0, a(n) = Sum_{k=0..n-1} prime(a(k)) * prime(a(n-k-1)).
%F G.f.: 1 + x * (Sum_{n>=0} prime(a(n)) * x^n)^2.
%t a[0] = 1; a[n_] := a[n] = Sum[Prime[a[k]] Prime[a[n - k - 1]], {k, 0, n - 1}]; Table[a[n], {n, 0, 9}]
%Y Cf. A000040, A000108, A007097, A014342.
%K nonn,hard,more
%O 0,2
%A _Ilya Gutkovskiy_, Nov 10 2020
%E a(10)-a(11) from _Daniel Suteu_, Nov 10 2020
%E a(12) from _Jinyuan Wang_, Nov 14 2020