A213721 Smallest prime that is the sum of four nonzero squares in exactly n ways.

2, 7, 31, 67, 97, 103, 157, 199, 277, 223, 307, 383, 439, 367, 547, 463, 673, 613, 577, 751, 643, 733, 787, 727, 853, 983, 997, 967, 1171, 1223, 1063, 1087, 1123, 1613, 1237, 1279, 1471, 1453, 1669, 1423, 1483, 1597, 1627, 1543, 1567, 1747, 2039, 1753, 1867, 1951

Offset: 0

Author

Arkadiusz Wesolowski, Nov 02 2012

Keywords

• nonn

Examples

			a(2) = 31 because 31 = 2*1 + 4 + 25 = 4 + 3*9.
		

Links

• Index entries for sequences related to sums of squares

Crossrefs

Cf. A025416.

Programs

Mathematica

lst = {}; Do[p = 2; While[True, If[PrimeQ[p] && Length@Select[PowersRepresentations[p, 4, 2], ! MemberQ[#, 0] &] == n, AppendTo[lst, p]; Break[]]; p++], {n, 0, 49}]; lst