A331078 a(n) = Sum_{k = 1..n} [u_2(k)*u_3(k)], where u_2 = A038548, u_3 = A034836.

1, 2, 3, 7, 8, 12, 13, 19, 23, 27, 28, 40, 41, 45, 49, 61, 62, 74, 75, 87, 91, 95, 96, 120, 124, 128, 134, 146, 147, 167, 168, 183, 187, 191, 195, 235, 236, 240, 244, 268, 269, 289, 290, 302, 314, 318, 319, 364, 368, 380, 384, 396, 397, 421, 425, 449, 453, 457, 458, 518, 519, 523, 535, 563, 567, 587, 588, 600, 604, 624

Offset: 1

Author

N. J. A. Sloane, Jan 10 2020

Keywords

• nonn

Comments

For background references see A330570.

Links

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

Crossrefs

Cf. A038548, A034836

Programs

Mathematica

s[1] = 1; s[n_] := Module[{e = FactorInteger[n][[;; , 2]]}, Ceiling[(Times @@ (e + 1)) / 2]*(If[IntegerQ[Surd[n, 3]], 1/3, 0] + (Times @@ ((e + 1)*(e + 2)/2))/6 + (Times @@ (Floor[e/2] + 1))/2)]; Accumulate[Array[s, 100]] (* Amiram Eldar, Apr 19 2024 *)