cp's OEIS Frontend

A275369 Least k such that n! divides sigma(k!) (k > 0).

%I A275369 #25 Aug 16 2016 09:48:18
%S A275369 1,3,3,5,5,8,14,19,19,23,23,30,30,31,50,50,50,50,50,51,51,64,90,90,91,
%T A275369 91,91,91,126,130,130,130,130,130,130,130,130,130,131,132,132,132,132,
%U A275369 132,134,134,234,234,234,234,236,236,236,236,288,288,288,288
%N A275369 Least k such that n! divides sigma(k!) (k > 0).
%H A275369 Robert Israel, <a href="/A275369/b275369.txt">Table of n, a(n) for n = 1..1100</a>
%e A275369 a(3) = 3 because 3! divides sigma(3!) = 12.
%p A275369 N:= 500: # to get a(1) .. a(N)
%p A275369 k:= 1; skf:= 1;
%p A275369 for n from 1 to N do
%p A275369   nf:= n!;
%p A275369   while skf mod nf <> 0 do
%p A275369     k:= k+1;
%p A275369     skf:= numtheory:-sigma(k!);
%p A275369   od:
%p A275369   A[n]:= k;
%p A275369 od:
%p A275369 seq(A[i],i=1..N); # _Robert Israel_, Aug 09 2016
%t A275369 Table[k = 1; While[! Divisible[DivisorSigma[1, k!], n!], k++]; k, {n, 58}] (* _Michael De Vlieger_, Aug 08 2016 *)
%o A275369 (PARI) a(n) = {my(k = 1); while(sigma(k!) % n! != 0, k++); k; }
%Y A275369 Cf. A000142, A062569.
%K A275369 nonn
%O A275369 1,2
%A A275369 _Altug Alkan_, Jul 29 2016