cp's OEIS Frontend

A071147 Smallest squarefree number k with exactly n prime factors such that the sum of the prime factors is divisible by the largest prime dividing k, or 0 if no such k exists.

%I A071147 #18 Feb 26 2022 15:53:01
%S A071147 1,2,0,30,3135,3570,72930,1231230,14804790,497668710,14908423530,
%T A071147 278196808890,12192694624110,550939666387110,21275256232500270,
%U A071147 1458502323630662310,87988283090327810190,3254611619240885033130,261462818462495728868790,9965666894849284108299810,557940830126698960967415390,90544636506979071680577724410
%N A071147 Smallest squarefree number k with exactly n prime factors such that the sum of the prime factors is divisible by the largest prime dividing k, or 0 if no such k exists.
%C A071147 No solution exists for n=2, so a(2)=0.
%F A071147 A008472(k)/A006530(k) is an integer; k is squarefree and has exactly n prime factors.
%e A071147 a(0) =       1 = 1;
%e A071147 a(1) =       2 = 2;
%e A071147 a(3) =      30 = 2 *  3 *  5;
%e A071147 a(4) =    3135 = 3 *  5 * 11 * 19;
%e A071147 a(5) =    3570 = 2 *  3 *  5 *  7 * 17;
%e A071147 a(6) =   72930 = 2 *  3 *  5 * 11 * 13 * 17;
%e A071147 a(7) = 1231230 = 2 *  3 *  5 *  7 * 11 * 13 * 41.
%Y A071147 Cf. A008472, A006530, A000961, A025475, A037074, A071139-A071146.
%K A071147 nonn
%O A071147 0,2
%A A071147 _Labos Elemer_, May 13 2002
%E A071147 Corrected and extended by _Donovan Johnson_, Apr 22 2008
%E A071147 Name corrected by _Jon E. Schoenfield_, Jul 08 2018