A356445 a(n) is the number of times that A064440(n) occurs as the sum of proper divisors function (A001065).

2, 3, 5, 7, 13, 17, 19, 23, 31, 41, 59, 61, 67, 79, 83, 97, 101, 109, 113, 127, 131, 139, 149, 151, 193, 199, 223, 227, 229, 277, 283, 317, 397, 433, 521, 541, 577, 607, 677, 743, 757, 811, 863, 881, 911, 971, 1031, 1049, 1063, 1093, 1249, 1319, 1373, 1433, 1489

Offset: 1

Author

Amiram Eldar, Sep 23 2022

Keywords

• nonn

Comments

The record values correspond to the terms of A064440.

All the terms are primes by definition.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..188

Crossrefs

Cf. A001065, A048138, A064440, A238895, A238896.

Programs

Mathematica

seq[max_] := Module[{s = Table[0, {n, 1, max}], i, v = {}, m = 0}, Do[If[(i = DivisorSigma[1, n] - n) <= max, s[[i]]++], {n, 2, (max - 1)^2}]; Do[If[s[[i]] > m && PrimeQ[s[[i]]], m = s[[i]]; AppendTo[v, s[[i]]]], {i, 1, max}]; v]; seq[2000]

Formula

a(n) = A048138(A064440(n)).