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

1,1

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

Formula

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

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]

Crossrefs

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

Sequence in context: A042992 A344621 A255203 * A233577 A233041 A049567

Adjacent sequences: A356442 A356443 A356444 * A356446 A356447 A356448

Keyword

nonn

Author

Amiram Eldar, Sep 23 2022

Status

approved