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 A181812 #8 May 15 2017 19:56:05 %S A181812 1,2,6,30,4,210,2310,12,30030,510510,60,9699690,36,8,223092870, %T A181812 6469693230,420,180,200560490130,4620,7420738134810,304250263527210, %U A181812 24,13082761331670030,900,60060,614889782588491410,1260,1021020,32589158477190044730 %N A181812 Range of values of A181811, in order of first appearance: a(n) = A181811(2n-1). %C A181812 a(n)=smallest integer that, upon multiplying any divisor of the n-th odd positive integer (A005408(n)), produces a member of A025487. %C A181812 A permutation of the members of A025487. %H A181812 Indranil Ghosh, <a href="/A181812/b181812.txt">Table of n, a(n) for n = 1..1000</a> %F A181812 If 2n-1 = Product p(i)^e(i), then a(n) = Product A002110(i-1)^e(i). I.e., a(n)= A181811(A005408(n)). %e A181812 For any divisor d of 15 (d = 1, 3, 5, 15), 12d (12, 36, 60, 180) is always a member of A025487. 12 is the smallest integer with this relationship to 15; therefore, since 15 = A005408(8), a(8)=12. %o A181812 (Python) %o A181812 from sympy import primerange, factorint %o A181812 from operator import mul %o A181812 def P(n): return reduce(mul, [i for i in primerange(2, n + 1)]) %o A181812 def a181811(n): %o A181812 f = factorint(n) %o A181812 return 1 if n==1 else (reduce(mul, [P(i)**f[i] for i in f]))/n %o A181812 def a(n): return a181811(2*n - 1) # _Indranil Ghosh_, May 15 2017 %K A181812 nonn %O A181812 1,2 %A A181812 _Matthew Vandermast_, Nov 30 2010