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%I #5 Dec 10 2016 21:55:08
%S 2,5,13,31,131,383,2143,7057,48197,193433,1483733,6898961,60231361,
%T 293988703,2808611363,15253406999,164272132459,925319250199,
%U 10930128162979,65091314708809,796351893424729,5081275480436251
%N Sum of the product of the first floor(n/2) even-indexed primes and the product of the first floor(n/2) odd-indexed primes.
%F Sum_{i=1..n} of the product_{j=2..n, 2} p_j (A066206) and the product_{k=1..n, 2} p_j (A066205).
%e a(5) = 2*5*11 + 3*7 = 131, a(6) = 2*5*11 + 3*7*13 = 383, a(7) =
%e 2*5*11*17 + 3*7*13 = 2143, a(8) = 2*5*11*17 + 3*7*13*19 = 7057.
%t f[n_] := Product[Prime[i], {i, 2, n, 2}] + Product[Prime[i], {i, 1, n, 2}]; f[1] = 2; Table[ f[n], {n, 22}]
%Y Cf. A095137, A000040, A066206, A066205.
%K nonn
%O 1,1
%A _Robert G. Wilson v_, May 27 2004
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