A303640 a(n) is the least k > n such that A007504(n) divides A007504(k).

3, 3, 9, 13, 33, 15, 121, 84, 103, 26, 259, 295, 433, 71, 111, 331, 317, 366, 649, 80, 283, 274, 429, 4542, 3071, 2138, 4241, 74, 761, 3083, 103, 1847, 1683, 3886, 1233, 470, 2359, 1182, 1797, 3431, 2037, 1767, 7543, 9106, 1867, 656, 5469, 6012, 12245, 2225

Offset

1,1

Comments

Credit is given for Zak Seidov for doing the calculations.

Links

Seiichi Manyama, Table of n, a(n) for n = 1..500

Example

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

Maple

N:= 10^5: # to get all terms before the first term > N
A007504:= ListTools:-PartialSums([seq(ithprime(i), i=1..N)]):
found:= true:
for n from 1 while found do
  found:= false;
  for k from n+1 to N do
    if A007504[k] mod A007504[n] = 0 then
      found:= true;
      A[n]:= k;
      break
    fi
  od
od:
seq(A[i], i=1..n-2); # Robert Israel, May 02 2018

Mathematica

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 *)

Crossrefs

Cf. A000040, A007504.

Sequence in context: A083336 A225436 A183811 * A091328 A348402 A138383

Adjacent sequences: A303637 A303638 A303639 * A303641 A303642 A303643

Keyword

nonn

Author

J. M. Bergot, Apr 27 2018

Extensions

More terms from Alois P. Heinz, Apr 27 2018

Status

approved