A284788 Even numbers that cannot be represented in at least two ways as the sum of two odd composites.

2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 32, 34, 38, 40, 44, 46, 52, 56, 62, 68

Offset: 1

Author

Bernard Schott, Apr 03 2017

Keywords

• fini
• full
• nonn

Comments

If n is even and n > 68, then n can be written as at least two distinct sums of two composite odd integers.

Examples

			34 is in the sequence because 34 = 9 + 25 but cannot be represented in a second way as the sum of two odd composites with 9, 15, 21, 25, 27, 33.
		

References

• D. Wells, The Penguin Dictionary of Curious and Interesting Numbers, 1997, page 111.

Crossrefs

Cf. A118081, A284787 (complement).

Programs

Mathematica

oddco = Select[Range[9, 100, 2], ! PrimeQ[#] &]; Select[Range[2, 100, 2],  Length@ Quiet@ IntegerPartitions[#, {2}, oddco, 2] < 2 &] (* Giovanni Resta, Apr 03 2017 *)