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 A338816 a(0) = 1; for n > 0, a(n) = Sum_{k=0..n-1} prime(a(k)) * prime(a(n-k-1)). 1
 1, 4, 28, 477, 15054, 716619, 46386636, 3829544473, 386956394842, 46498297487679, 6503866348955704, 1041432998153210277, 188367392877258840974 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 LINKS Table of n, a(n) for n=0..12. FORMULA G.f.: 1 + x * (Sum_{n>=0} prime(a(n)) * x^n)^2. MATHEMATICA 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}] CROSSREFS Cf. A000040, A000108, A007097, A014342. Sequence in context: A086812 A197872 A203220 * A111817 A134048 A091969 Adjacent sequences: A338813 A338814 A338815 * A338817 A338818 A338819 KEYWORD nonn,hard,more AUTHOR Ilya Gutkovskiy, Nov 10 2020 EXTENSIONS a(10)-a(11) from Daniel Suteu, Nov 10 2020 a(12) from Jinyuan Wang, Nov 14 2020 STATUS approved

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Last modified August 9 11:10 EDT 2024. Contains 375040 sequences. (Running on oeis4.)