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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 April 22 10:29 EDT 2019. Contains 322330 sequences. (Running on oeis4.)