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 A303640 a(n) is the least k > n such that A007504(n) divides A007504(k). 1
 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 (list; graph; refs; listen; history; text; internal format)
 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

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Last modified September 7 13:04 EDT 2024. Contains 375730 sequences. (Running on oeis4.)