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 A057449 #32 Aug 16 2024 21:11:27
%S A057449 1,1,2,2,4,3,6,8,12,15,10,12,12,35,40,64,16,81,18,100,112,99,22,192,
%T A057449 80,143,216,588,28,600,30,1024,352,255,224,1944,36,323,520,2400,40,
%U A057449 3087,42,3388,2880,483,46,12288,252,5625,952,6084,52,19683,1056,14112,1216
%N A057449 Product of differences between consecutive positive divisors of n.
%C A057449 Row products of triangle A193829, if n >= 2. - _Omar E. Pol_, Aug 31 2011
%C A057449 When p is prime a(p) = p-1. - _Michel Marcus_, May 15 2014
%H A057449 Alois P. Heinz, <a href="/A057449/b057449.txt">Table of n, a(n) for n = 1..10000</a>
%F A057449 a(n) = Product_{k=1..A000005(n)-1} A027750(n,k+1)-A027750(n,k). - _Reinhard Zumkeller_, Jun 23 2013
%e A057449 Since positive divisors of 12 are 1, 2, 3, 4, 6 and 12, a(12) = (2-1) *(3-2) *(4-3) *(6-4) *(12-6) = 1 *1 *1 *2 *6 = 12.
%t A057449 Times@@Differences[Divisors[#]]&/@Range[80] (* _Harvey P. Dale_, Apr 20 2011 *)
%o A057449 (Haskell)
%o A057449 a057449 = product . a193829_row -- _Reinhard Zumkeller_, Jun 23 2013
%o A057449 (PARI) a(n) = {my(d = divisors(n)); prod(i=1, #d-1, d[i+1] - d[i]);} \\ _Michel Marcus_, May 15 2014
%K A057449 nonn,look
%O A057449 1,3
%A A057449 _Leroy Quet_, Sep 25 2000