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 A158977 #9 Sep 08 2022 08:45:43
%S A158977 1,2,6,24,30,720,210,6720,1890,8400,2310,47900160,30030,1681680,
%T A158977 4054050,15375360,510510,1984862880,9699690,62078016000,1833241410,
%U A158977 853572720,223092870,1776404640890880,5577321750,23201658480,54211567410
%N A158977 Product of the numbers k in the range 1 <= k <= n such that the proper divisors of k are a subset of the proper divisors of n.
%C A158977 Here, proper divisors include 1 but not the argument (k or n, respectively) in the divisor set, as counted in A032741.
%F A158977 If p is prime, a(p) = A034386(p).
%F A158977 a(n)*A158978(n) = A000142(n). - _R. J. Mathar_, Apr 06 2009
%e A158977 a(8) = 6720 is the product of the 7 numbers k: 1 {1}, 2 {1}, 3 {1}, 4 {1, 2}, 5 {1}, 7 {1}, 8 {1, 2, 4} with divisor set that are subsets of {1, 2, 4} for n = 8. 1 * 2 * 3 * 4 * 5 * 7 * 8 = 6720.
%o A158977 (Magma) [ &*[ k: k in [1..n] | forall(t){ d: d in Divisors(k) | d eq k or d in Divisors(n) } ]: n in [1..27] ]; // _Klaus Brockhaus_, Apr 07 2009
%Y A158977 Cf. A159073, A034386.
%K A158977 nonn
%O A158977 1,2
%A A158977 _Jaroslav Krizek_, Apr 01 2009
%E A158977 Edited by _R. J. Mathar_, Apr 06 2009
%E A158977 More terms from _Klaus Brockhaus_, Apr 07 2009