A303640 - OEIS

%I #24 Mar 22 2019 13:59:15

%S 3,3,9,13,33,15,121,84,103,26,259,295,433,71,111,331,317,366,649,80,

%T 283,274,429,4542,3071,2138,4241,74,761,3083,103,1847,1683,3886,1233,

%U 470,2359,1182,1797,3431,2037,1767,7543,9106,1867,656,5469,6012,12245,2225

%N a(n) is the least k > n such that A007504(n) divides A007504(k).

%C Credit is given for _Zak Seidov_ for doing the calculations.

%H Seiichi Manyama, <a href="/A303640/b303640.txt">Table of n, a(n) for n = 1..500</a>

%e A007504(6)=41 and 41|328=A007504(15).

%p N:= 10^5: # to get all terms before the first term > N

%p A007504:= ListTools:-PartialSums([seq(ithprime(i),i=1..N)]):

%p found:= true:

%p for n from 1 while found do

%p   found:= false;

%p   for k from n+1 to N do

%p     if A007504[k] mod A007504[n] = 0 then

%p       found:= true;

%p       A[n]:= k;

%p       break

%p     fi

%p   od

%p od:

%p seq(A[i],i=1..n-2); # _Robert Israel_, May 02 2018

%t a[n_] := For[tpn = Prime[Range[n]] // Total; tpk = 0; k = n+1, True, k++, tpk += Prime[k]; If[Divisible[tpk, tpn], Return[k]]]; Array[a, 50] (* _Jean-François Alcover_, Mar 22 2019 *)

%Y Cf. A000040, A007504.

%K nonn

%O 1,1

%A _J. M. Bergot_, Apr 27 2018

%E More terms from _Alois P. Heinz_, Apr 27 2018