A352231 Numbers that can be expressed as the sum of two primes in exactly 9 ways.

90, 132, 170, 196, 202, 220, 230, 236, 238, 244, 250, 254, 262, 268, 302, 314, 338, 346, 356, 388, 428, 458, 488

Offset: 1

Author

Wesley Ivan Hurt, Mar 08 2022

Keywords

• nonn
• more

Examples

			90 = 7+83 = 11+79 = 17+73 = 19+71 = 23+67 = 29+61 = 31+59 = 37+53 = 43+47.
		

Crossrefs

Numbers that can be expressed as the sum of two primes in k ways for k=0..10: A014092 (k=0), A067187 (k=1), A067188 (k=2), A067189 (k=3), A067190 (k=4), A067191 (k=5), A066722 (k=6), A352229 (k=7), A352230 (k=8), this sequence (k=9), A352233 (k=10).

Cf. A000954, A023036, A061358.

Programs

Mathematica

c[n_] := Count[IntegerPartitions[n, {2}], ?(And @@ PrimeQ[#] &)]; Select[Range[1000], c[#] == 9 &] (* _Amiram Eldar, Mar 08 2022 *)

Formula

A061358(a(n)) = 9. - Alois P. Heinz, Mar 08 2022