A078386 Squarefree kernels of numbers which can be written as sum of a positive square and a positive cube.

2, 5, 3, 10, 6, 17, 6, 26, 14, 31, 33, 6, 37, 43, 22, 10, 26, 57, 21, 65, 34, 6, 73, 38, 10, 82, 89, 91, 10, 101, 6, 113, 122, 42, 127, 2, 129, 134, 141, 145, 74, 30, 38, 161, 82, 170, 57, 174, 177, 185, 21, 14, 197, 102, 206, 26, 217, 110, 223, 15, 226, 58, 233, 241

Offset: 1

Author

Reinhard Zumkeller, Nov 25 2002

Keywords

• nonn

Examples

			A055394(12) = 3^2+3^3 = 36, a(12) = A007947(A055394(12)) = A007947(36) = A007947(2^2*3^2) = 2*3 = 6.
		

Links

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

Crossrefs

Cf. A007947, A055394, A078387.

Programs

Mathematica

Times @@ FactorInteger[#][[;; , 1]] & /@ Select[Range[300], Length[Reduce[a^2 + b^3 == # && a > 0 && b > 0, {a, b}, Integers]] > 0 &] (* Amiram Eldar, Mar 27 2025 *)

Formula

a(n) = A007947(A055394(n)).