A078384 -id:A078384 - cp's OEIS frontend

A078382 Sum of divisors of numbers which can be written as sum of a positive square and a positive cube.

3, 6, 13, 18, 28, 18, 60, 42, 56, 32, 48, 91, 38, 44, 84, 93, 98, 80, 104, 84, 126, 195, 74, 140, 186, 126, 90, 112, 217, 102, 280, 114, 186, 312, 128, 255, 176, 204, 192, 180, 266, 372, 300, 192, 294, 324, 260, 360, 240, 228, 320, 399, 198, 504, 312, 434, 256

Offset: 1

Reinhard Zumkeller, Nov 25 2002

nonn

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

Cf. A000203, A055394, A078381, A078383, A078384.

DivisorSigma[1, Select[Range[200], Length[Reduce[a^2 + b^3 == # && a > 0 && b > 0, {a, b}, Integers]] > 0 &]] (* Amiram Eldar, Mar 27 2025 *)

a(n) = A000203(A055394(n)).

A078383 Sum of distinct prime factors of numbers which can be written as sum of a positive square and a positive cube.

Original entry on oeis.org

2, 5, 3, 7, 5, 17, 5, 15, 9, 31, 14, 5, 37, 43, 13, 7, 15, 22, 10, 18, 19, 5, 73, 21, 7, 43, 89, 20, 7, 101, 5, 113, 63, 12, 127, 2, 46, 69, 50, 34, 39, 10, 21, 30, 43, 24, 22, 34, 62, 42, 10, 9, 197, 22, 105, 15, 38, 18, 223, 8, 115, 31, 233, 241, 46, 12, 257, 20, 16, 58, 269

Offset: 1

Reinhard Zumkeller, Nov 25 2002

nonn

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

Cf. A008472, A055394, A078377, A078382, A078384.

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

a(n) = A008472(A055394(n)).

cp's OEIS Frontend

A078382 Sum of divisors of numbers which can be written as sum of a positive square and a positive cube.

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