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 A073820 #2 Mar 31 2012 13:20:45 %S A073820 1,2,3,2,3,2,3,4,5,4,5,6,7,5,6,7,8,9,8,9,10,10,11,12,13,10,11,12,13, %T A073820 14,15,16,15,16,17,17,18,14,15,16,17,18,19,20,21,22,23,24,25,20,21,22, %U A073820 23,24,25,26,27,24,25,26,27,28,29,30,31,32,33,34,32,33,31,30,31,32,33,34 %N A073820 a(n) = n+1-i such that prime(i)*(n+1-i) is maximized (1 <= i <= n). %C A073820 3 is the only n for which the maximum is not unique; a(3) could also be given as 2. %F A073820 a(n) = A073818(n)/A073819(n). %e A073820 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) = 3. %Y A073820 Cf. A073818, A073819. %K A073820 easy,nonn %O A073820 1,2 %A A073820 _David Wasserman_, Aug 13 2002