cp's OEIS Frontend

A324853 First number divisible by n of its own distinct prime indices.

%I A324853 #18 Aug 19 2019 13:30:53
%S A324853 1,2,6,30,330,4290,60060,1021020,29609580,917896980,33962188260,
%T A324853 1290563153880,52913089309080,2275262840290440,106937353493650680,
%U A324853 6309303856125390120,422723358360401138040,30013358443588480800840,2190975166381959098461320
%N A324853 First number divisible by n of its own distinct prime indices.
%C A324853 A prime index of n is a number m such that prime(m) divides n. The multiset of prime indices of n is row n of A112798.
%C A324853 a(n) is the first position of n in A324852.
%H A324853 Rémy Sigrist, <a href="/A324853/a324853.txt">C program for A324853</a>
%e A324853 a(6) = 60060 = 2^2 * 3 * 5 * 7 * 11 * 13 has prime indices {1,1,2,3,4,5,6}, and is less than any other number divisible by six of its own distinct prime indices.
%t A324853 nn=10000;
%t A324853 With[{mgs=Table[Count[If[n==1,{},FactorInteger[n]],{p_,_}/;Divisible[n,PrimePi[p]]],{n,nn}]},Table[Position[mgs,i][[1,1]],{i,0,5}]]
%o A324853 (C) See Links section.
%o A324853 (PARI) isok(k,n) = {my(f=factor(k)[,1]); sum(j=1, #f, !(k % primepi(f[j]))) == n;}
%o A324853 a(n) = {my(k=1); while (!isok(k, n), k++); k;} \\ _Michel Marcus_, Mar 20 2019
%Y A324853 Cf. A000720, A001222, A003963, A056239, A120383, A323440.
%Y A324853 Cf. A324771, A324846, A324847, A324848, A324849, A324850, A324852, A324856.
%K A324853 nonn,more
%O A324853 0,2
%A A324853 _Gus Wiseman_, Mar 18 2019
%E A324853 a(8)-a(9) from _Rémy Sigrist_, Mar 19 2019
%E A324853 a(10)-a(18) from _Michel Lagneau_, Aug 19 2019