A078388 Arithmetic derivative of numbers which can be written as sum of a positive square and a positive cube.

1, 1, 6, 7, 16, 1, 44, 15, 32, 1, 14, 60, 1, 1, 48, 45, 56, 22, 51, 18, 72, 156, 1, 80, 176, 43, 1, 20, 140, 1, 216, 1, 63, 165, 1, 448, 46, 69, 50, 34, 152, 185, 236, 30, 168, 129, 123, 151, 62, 42, 216, 252, 1, 284, 105, 432, 38, 284, 1, 240, 115, 356, 1, 1, 211, 456

Offset

1,3

Links

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

Formula

a(n) = A003415(A055394(n)). - Amiram Eldar, Mar 27 2025

Mathematica

ad[n_] := n * Plus @@ ((Last[#]/First[#]) & /@ FactorInteger[n]); ad /@ Select[Range[300], Length[Reduce[a^2 + b^3 == # && a > 0 && b > 0, {a, b}, Integers]] > 0 &] (* Amiram Eldar, Mar 27 2025 *)

Crossrefs

Cf. A003415, A055394, A078386.

Sequence in context: A396083 A106680 A214325 * A344222 A315843 A261195

Adjacent sequences: A078385 A078386 A078387 * A078389 A078390 A078391

Keyword

nonn

Author

Reinhard Zumkeller, Nov 25 2002

Status

approved