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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
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
Sequence in context: A020749 A120135 A162704 * A314412 A314413 A314414
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.)