A360520 a(n) = A120963(n) + A341711(floor(n/2)).

2, 3, 11, 15, 43, 57, 137, 177, 389, 495, 1003, 1257, 2421, 3003, 5515, 6771, 12011, 14631, 25143, 30399, 50931, 61197, 100161, 119643, 192051, 228255, 359839, 425631, 660623, 778119, 1190359, 1396479, 2109119, 2465439, 3679263, 4286175, 6327871, 7348719

Offset

0,1

Links

Jean-François Alcover, Table of n, a(n) for n = 0..1000

Example

n=4: a(4) = A120963(4) + A341711(2) = 24 + 19 = 43.

Maple

with(numtheory):
b:= proc(n) option remember; nops(invphi(n)) end:
g:= proc(n) option remember; `if`(n=0, 1, add(
      g(n-j)*add(d*b(d), d=divisors(j)), j=1..n)/n)
    end:
a:= n-> g(n)+g(2*iquo(n, 2)+1)/2:
seq(a(n), n=0..40);  # Alois P. Heinz, Mar 02 2023

Mathematica

b[n_] := b[n] = Length[invphi[n]];
g[n_] := g[n] = If[n == 0, 1, Sum[g[n - j]*Sum[d*b[d], {d, Divisors[j]}], {j, 1, n}]/n];
a[n_] := g[n] + g[2*Quotient[n, 2] + 1]/2;
Table[a[n], {n, 0, 100}] (* Jean-François Alcover, Nov 16 2023, after Alois P. Heinz and using Maxim Rytin's invphi program (see A007617) *)

Crossrefs

Cf. A120963, A341711.

Sequence in context: A293026 A178430 A295128 * A066687 A144979 A194558

Adjacent sequences: A360517 A360518 A360519 * A360521 A360522 A360523

Keyword

nonn

Author

N. J. A. Sloane, Mar 02 2023

Status

approved