A224773 One half of the even terms of A224771.

7, 13, 15, 19, 21, 23, 25, 27, 31, 33, 35, 37, 39, 43, 45, 47, 49, 53, 55, 57, 59, 61, 63, 67, 69, 71, 73, 75, 77, 79, 81, 83, 85, 87, 89, 91, 93, 95, 97, 99, 101, 103, 105, 107, 109, 111, 113, 115, 117, 119, 121, 123, 125, 127, 129, 131, 133, 135, 137, 139

Offset: 1

Author

Wolfdieter Lang, Apr 19 2013

Keywords

• nonn

Comments

2*a(n), n >= 1, gives all even numbers representable as a primitive sum of three distinct nonzero squares.

The numbers a(n) are of interest in a problem related to integer solutions for the curvatures of the Descartes-Steiner circle theorem.

Examples

			a(1) = 7 because the first even term of A224771 is 14 (m = 1).
a(9) = 31 because 62 is the ninth even term of A224771 (m = 18).
		

Links

• Eric Weisstein's World of Mathematics, Descartes Circle Theorem.

Crossrefs

Cf. A224771.

Formula

a(n) is one half of the n-th even term of A224771.