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a(n) = prime(i) such that prime(i)*(n+1-i) is maximized (1 <= i <= n).
2

%I #2 Mar 31 2012 13:20:45

%S 2,2,2,5,5,11,11,11,11,17,17,17,17,29,29,29,29,29,37,37,37,41,41,41,

%T 41,59,59,59,59,59,59,59,67,67,67,71,71,97,97,97,97,97,97,97,97,97,97,

%U 97,97,127,127,127,127,127,127,127,127,149,149,149,149,149,149,149,149

%N a(n) = prime(i) such that prime(i)*(n+1-i) is maximized (1 <= i <= n).

%C 3 is the only n for which the maximum is not unique; a(3) could also be given as 3.

%F a(n) = A073818(n)/A073820(n).

%e For n = 5, we take the first 5 primes in ascending order and multiply them by the numbers from 5 to 1 in descending order: 2*5 = 10 3*4 = 12 5*3 = 15 7*2 = 14 11*1 = 11 The largest product is 15, so a(5) = 5.

%Y Cf. A073818, A073820.

%K easy,nonn

%O 1,1

%A _David Wasserman_, Aug 13 2002