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.

5, 8, 12, 18, 52, 100, 946

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