This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A073819 #2 Mar 31 2012 13:20:45 %S A073819 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 A073819 41,59,59,59,59,59,59,59,67,67,67,71,71,97,97,97,97,97,97,97,97,97,97, %U A073819 97,97,127,127,127,127,127,127,127,127,149,149,149,149,149,149,149,149 %N A073819 a(n) = prime(i) such that prime(i)*(n+1-i) is maximized (1 <= i <= n). %C A073819 3 is the only n for which the maximum is not unique; a(3) could also be given as 3. %F A073819 a(n) = A073818(n)/A073820(n). %e A073819 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 A073819 Cf. A073818, A073820. %K A073819 easy,nonn %O A073819 1,1 %A A073819 _David Wasserman_, Aug 13 2002