A089294 Smallest prime p_k such that n can be written as a "plus-minus" sum n=sum_(i=1..k)e_i*(p_i)^2 with distinct primes p_i<=p_k, where e_i is 1 or -1.

19, 13, 19, 13, 2, 3, 13, 19, 13, 3, 13, 7, 5, 3, 13, 7, 5, 13, 13, 7, 5, 5, 13, 13, 7, 5, 13, 13, 7, 5, 5, 13, 13, 7, 5, 13, 7, 7, 5, 13, 7, 17, 11, 11, 7, 7, 17, 11, 13, 7, 17, 11, 11, 7, 7, 17, 11, 13, 7, 11, 11, 7, 7, 11, 13, 7, 17, 11, 11, 7, 7, 17, 11, 13, 7, 17, 11, 11, 7, 7, 17, 11

Offset: 0

Author

W. Edwin Clark Nov 06 2003

Keywords

• nonn

Comments

The first terms where this sequence differs from A088934 are n=22,31,52,87,89,98,118,127,...

Examples

			a(22)=13 because 22 can be represented as -13^2+11^2+7^2+5^2-2^2.
The corresponding representation with the minimum number of terms is
22=19^2-13^2-11^2-7^2 (A088934(22)=19, A088910(22)=4 terms)
		

Crossrefs

The positions of the records in this sequence are given in A089295. Cf. A088910, A088934.