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 A134650 Numbers n such that n is the sum of two consecutive primes (i.e., in A001043) but is not the sum of two sums of two consecutive primes. 2
 5, 8, 12, 18, 52, 100, 946 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers in A001043 but not in A134651. Conjectured to be finite, may be complete. a(8), if it exists, is greater than 20100000. - R. J. Mathar, Jan 26 2008 REFERENCES R. K. Guy, ed., Unsolved Problems, Western Number Theory Meeting, Las Vegas, 1988. LINKS Table of n, a(n) for n=1..7. MAPLE with(numtheory): Sset := {}: for i to 15000 do Sset := `union`(Sset, {ithprime(i) + ithprime(i + 1)}) od: Sset := convert(Sset, list): for n from 1 to nops(Sset) do count := 0: s := Sset[n]: for i from 1 to n do if member(s - Sset[i], Sset) and s-Sset[i] >= s/2 then count := count + 1 fi; od: if count = 0 then printf(`%d, `, Sset[n]) fi; od: # James A. Sellers, Jan 28 2008 CROSSREFS Cf. A001043, A134651, A135045. Sequence in context: A020749 A120135 A162704 * A314412 A314413 A314414 Adjacent sequences: A134647 A134648 A134649 * A134651 A134652 A134653 KEYWORD nonn,more AUTHOR N. J. A. Sloane, Jan 25 2008 EXTENSIONS 946 found by James A. Sellers, Jan 25 2008 STATUS approved

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Last modified February 21 20:41 EST 2024. Contains 370237 sequences. (Running on oeis4.)