A106562 Perfect squares which are not the sum of two primes.

1, 121, 289, 529, 625, 961, 1521, 1681, 2025, 2601, 2809, 3249, 3481, 4225, 4489, 5329, 6241, 6561, 6889, 7225, 7569, 8281, 9025, 9409, 9801, 10201, 11025, 11881, 12321, 12769, 13225, 15129, 15625, 16641, 17689, 18769, 19881, 20449, 21609

Offset: 1

Author

Alexandre Wajnberg, May 09 2005

Keywords

• easy
• nonn

Examples

			a(2)=121 because it is the second perfect square which is impossible to obtain summing two primes.
100 is not in the sequence because 100=97+3 (sum of two primes).
		

Crossrefs

Cf. A106544-A106548, A106563-A106564, A106571, A106573-A106575, A106577.

Programs

Mathematica

Select[Range[150]^2,Count[IntegerPartitions[#,{2}],?(AllTrue[#,PrimeQ]&)]==0&] (* _Harvey P. Dale, Aug 14 2025 *)

Formula

A106544 with 0's removed.

Extensions

Extended by Ray Chandler, May 12 2005