A206280 Smallest of four consecutive primes whose sum is a square.

5, 73, 137, 433, 569, 1217, 5171, 15859, 16631, 32027, 35677, 37619, 39191, 45767, 59029, 63997, 65011, 77813, 92401, 103669, 186601, 196201, 230387, 237161, 261089, 273517, 439559, 463747, 484397, 488573, 505511, 514079, 519803, 538739, 544627, 633599

Offset: 1

Author

Harvey P. Dale, Feb 05 2012

Keywords

• nonn
• easy

Examples

			a(4) = 433. The next three primes are 439, 443, and 449, and the sum of those four primes = 1764 = 42^2.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000040, A061275, A072849, A206279, A206281.

Programs

Mathematica

Transpose[Select[Partition[Prime[Range[80000]],4,1],IntegerQ[Sqrt[ Total[#]]]&]][[1]]

Formula

a(n) = A000040(A072849(n)). - Amiram Eldar, Jun 28 2024