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 A060837 #11 Feb 18 2014 23:17:51 %S A060837 1,2,4,3,9,8,12,18,16,5,25,6,20,72,48,50,36,7,45,75,49,32,28,80,200, %T A060837 98,64,27,63,147,81,10,108,288,112,150,180,392,192,162,100,11,175,245, %U A060837 121,24,44,90,432,800,252,294,320,648,300,242,144,13,99,675,405,363,169,14 %N A060837 List the positive rationals in the canonical order A020652(n)/A020653(n) and apply the Sagher map to turn them into integers. %C A060837 The Sagher map sends Product p_i^e_i / Product q_i^f_i (p_i and q_i being distinct primes) to Product p_i^(2e_i) * Product q_i^(2f_i-1). This map is multiplicative. %H A060837 Reinhard Zumkeller, <a href="/A060837/b060837.txt">Table of n, a(n) for n = 1..10000</a> %H A060837 Y. Sagher, <a href="http://www.jstor.org/stable/2324846">Counting the rationals</a>, Amer. Math. Monthly, 96 (1989), p. 823. Math. Rev. 90i:04001. %F A060837 a(n) = A020652(n)^2 * product(A027748(m,k)^(2*A124010(m,k)-1): m=a020653(n), k=1..A000005(m)). - _Reinhard Zumkeller_, Feb 16 2014 %e A060837 The first few rationals and their images are 1/1 -> 1, 1/2 -> 2, 2/1 -> 4, 1/3 -> 3, 3/1 -> 9, 1/4 -> 8, ... %o A060837 (Haskell) %o A060837 a060837 n = (a020652 n ^ 2) * %o A060837 product (zipWith (^) (a027748_row m) %o A060837 (map ((subtract 1) . (* 2)) (a124010_row m))) %o A060837 where m = a020653 n %o A060837 -- _Reinhard Zumkeller_, Feb 16 2014 %Y A060837 Cf. A038566, A071970. %K A060837 nonn,nice,easy %O A060837 1,2 %A A060837 _N. J. A. Sloane_, Jun 19 2002 %E A060837 More terms from Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), Jan 12 2003 %E A060837 Corrected by _Charles R Greathouse IV_, Sep 02 2009 %E A060837 Definition slightly changed by _Reinhard Zumkeller_, Feb 16 2014