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 A181820 #16 Mar 25 2023 12:07:54 %S A181820 1,2,3,4,5,6,7,10,8,11,9,14,12,13,15,22,20,17,21,18,26,16,25,28,19,33, %T A181820 30,34,24,35,44,23,39,42,38,40,55,27,52,29,50,51,36,49,66,46,56,65,45, %U A181820 68,31,70,57,32,60,77,78,58,88,85,63,76,37,110,69,48,84,91,75,102,62,54,98,104,95 %N A181820 a(1) = 1; for n > 1, if A025487(n) = Product p(i)^e(i), then a(n) = Product p(e(i)). %C A181820 A permutation of the positive integers. %C A181820 The partition given by the prime signature of A025487(n) has Heinz number a(n). - _Pontus von Brömssen_, Mar 25 2023 %H A181820 Amiram Eldar, <a href="/A181820/b181820.txt">Table of n, a(n) for n = 1..10000</a> %H A181820 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the positive integers</a> %F A181820 a(n) = A181819(A025487(n)). %F A181820 a(n) = A122111(A181815(n)). %e A181820 A025487(8) = 24 = 2^3*3 has the exponents (3,1) in its canonical prime factorization. Accordingly, a(8) = prime(3)*prime(1) (i.e., A000040(3)*A000040(1)), which equals 5*2=10. %Y A181820 A181815 is another mapping from the members of A025487 to the positive integers. Also see A181819, A181821. %Y A181820 Cf. A000040, A122111, A361808 (inverse), A361809 (fixed points). %K A181820 nonn %O A181820 1,2 %A A181820 _Matthew Vandermast_, Dec 07 2010