cp's OEIS Frontend

A083872 Triangle read by rows in which row n lists first appearance of m such that m divides n!.

%I A083872 #11 Sep 18 2017 09:27:52
%S A083872 1,2,3,6,4,8,12,24,5,10,15,20,30,40,60,120,9,16,18,36,45,48,72,80,90,
%T A083872 144,180,240,360,720,7,14,21,28,35,42,56,63,70,84,105,112,126,140,168,
%U A083872 210,252,280,315,336,420,504,560,630,840,1008,1260,1680,2520,5040,32,64
%N A083872 Triangle read by rows in which row n lists first appearance of m such that m divides n!.
%C A083872 Differs from A110797 starting at a(17)=9.
%C A083872 From _Rémy Sigrist_, Sep 17 2017: (Start)
%C A083872 Each number k > 0 appears exactly once in the triangle, on row A002034(k).
%C A083872 The n-th row of the triangle:
%C A083872 - contains A038024(n) terms,
%C A083872 - starts with A046021(n),
%C A083872 - ends with n! = A000142(n).
%C A083872 (End)
%H A083872 Rémy Sigrist, <a href="/A083872/b083872.txt">Rows n = 1..17, flattened</a>
%e A083872 1!:1
%e A083872 2!:1,2 -> 2 as 1 has already appeared
%e A083872 3!:1,2,3,6 -> 3,6
%e A083872 4!:1,2,3,4,6,8,12,24 -> 4,8,12,24
%t A083872 lst = {1}; Do[lst = Join[lst, Complement[Divisors[n!], Divisors[(n - 1)!]]], {n, 2, 9}]; lst (* _Vladimir Joseph Stephan Orlovsky_, Jul 07 2011 *)
%Y A083872 Cf. A000142, A002034, A038024, A046021.
%K A083872 nonn,tabf,look
%O A083872 1,2
%A A083872 _Jon Perry_, Jun 18 2003
%E A083872 Extended by _Ray Chandler_, Aug 23 2005