A283248 Numbers that cannot be represented as a sum of one prime and two primes squared.

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 14, 17, 22, 28, 33, 38, 43, 62, 68, 78, 83, 98, 104, 134, 146, 158, 174, 179, 182, 188, 200, 218, 230, 248, 260, 266, 272, 278, 302, 308, 314, 328, 332, 338, 356, 374, 398, 404, 416, 428, 440, 458, 464, 482, 488, 494, 506, 518, 524, 530

Offset: 1

Author

Michel Marcus, Mar 05 2017

Keywords

• nonn

Examples

			10 is the first missing number since it is 2 + 2^2 + 2^2.
		

Links

• Michel Marcus, Table of n, a(n) for n = 1..1000
• Hongze Li, Sums of one prime and two prime squares, Acta Arithmetica (2008), Volume: 134, Issue: 1, page 1-9.
• Lilu Zhao, The additive problem with one prime and two squares of primes, Journal of Number Theory, Volume 135, February 2014, Pages 8-27.

Crossrefs

Cf. A214879.

Programs

PARI

isok2(n)=forprime(q=2,sqrtint(n),if(isprimepower(n-q^2)==2, return(0))); 1;
isok(n) = forprime(p=2, n-1, if (!isok2(n-p), return (0));); 1;