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A234540
Nonprimes k that divide the sum of the nonprimes up to k.
0
1, 22, 25, 118, 414, 2745, 10623, 63201, 1039161, 1693864, 2285297, 52962021, 66998865, 232974402, 315796805, 336125877, 834972771, 1233903294, 1309750075, 1617454215, 2056836133, 5455816485, 8589896196, 9030058217, 10622144467, 12324258770, 33725308558
OFFSET
1,2
COMMENTS
Standard heuristics suggest that this sequence is infinite. - Charles R Greathouse IV, Dec 29 2013
EXAMPLE
a(2) = 22 because 1 + 4 + 6 + 8 + 9 + 10 + ... + 22 = 176 and 176/22 = 8.
MATHEMATICA
s = 0; Do[If[PrimeQ[k], Continue[]]; s += k; If[Mod[s, k] == 0, Print[k]], {k, 10^10}] (* Gomez *)
Select[Range[10^4], Not[PrimeQ[#]] && Divisible[Sum[Boole[Not[PrimeQ[m]]]m, {m, #}], #] &] (* Alonso del Arte, Dec 29 2013 *)
PROG
(PARI) v=List([s=1]); forcomposite(n=4, 1e9, if(s%n==0, listput(v, n)); s+=n); Vec(v) \\ Charles R Greathouse IV, Dec 29 2013
CROSSREFS
Cf. A007506.
Sequence in context: A045096 A227408 A303304 * A352158 A124177 A260990
KEYWORD
nonn
AUTHOR
EXTENSIONS
a(14)-a(27) from Donovan Johnson, Dec 30 2013
STATUS
approved