A104230 Minimal number of primes needed to sum to n^2.

2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 2, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2, 3, 2, 3, 2, 2, 2, 2, 2, 3, 2, 3, 2, 2, 2

Offset: 2

Author

Giovanni Teofilatto, Apr 02 2005

Keywords

• easy
• nonn

Comments

For the Goldbach conjecture every even number that is greater than 2 is the sum of three primes and odd number is the sum of three primes, no term is greater 3.

Examples

			a(2)=2 because 2^2=2+2;
a(3)=2 because 3^2=2+7.
		

Links

• Eric Weisstein's World of Mathematics, Goldbach Conjecture .

Formula

a(n) = A051034(A000290(n)). - Michel Marcus, Jun 04 2013

Extensions

Corrected and extended by Michel Marcus, Jun 04 2013