A063072 -id:A063072 - cp's OEIS frontend

A007626 Sum of divisors of superabundant numbers (A004394).

1, 3, 7, 12, 28, 60, 91, 124, 168, 360, 546, 744, 1170, 2418, 2880, 4368, 5952, 9360, 19344, 39312, 59520, 99944, 112320, 232128, 471744, 714240, 1199328, 1451520, 2437344, 2926080, 3249792, 6604416, 9999360

Offset: 1

Walter Nissen

Local maxima of sigma(n), the sum of divisors function A000203.

Same as A063072 for the first 19 terms. - T. D. Noe, Jul 01 2008

Amiram Eldar, Table of n, a(n) for n = 1..6863 (terms 1..500 from T. D. Noe)

Cf. A002192, A000203, A051444, A004394.

See A034885 and A002093 for another version.

Reap[ For[ n=1; a=0, n <= 3*10^6, n++, s = DivisorSigma[1, n]; b = s/n; If[ b>a, a=b; Print[s]; Sow[s]]]][[2, 1]] (* Jean-François Alcover, Apr 02 2013 *)
Join[{1},DeleteDuplicates[Select[{#[[1]],#[[2]],#[[2]]/#[[1]]}&/@Table[ {n,DivisorSigma[1,n]}, {n,10^6}],#[[3]]>1&],GreaterEqual[#1[[3]],#2[[3]]]&][[All,2]]] (* The program generates the first 31 terms of the sequence. *) (* Harvey P. Dale, Oct 04 2022 *)

a(n) = A000203(A004394(n)). - Amiram Eldar, Sep 25 2021

A256259 Sum of divisors of the minimal numbers (A007416).

Original entry on oeis.org

1, 3, 7, 12, 28, 31, 60, 91, 124, 168, 127, 360, 403, 546, 508, 744, 1170, 1651, 2418, 2880, 2821, 3048, 2047, 4368, 3751, 5952, 9360, 9906, 8188, 12493, 8191, 19344, 15367, 22568, 22506, 24384, 28800, 26611, 39312, 32764, 51181, 59520, 49128, 79248, 99944, 92202, 112320, 116281, 106483, 160797

Offset: 1

Omar E. Pol, Apr 20 2015

nonn

Has a symmetric representation in the same way as A000203 and all its subsequences.

Amiram Eldar, Table of n, a(n) for n = 1..10000 (calculated from the b-file at A007416)

Cf. A000203, A005179, A007416, A007626, A053212, A063072, A081533, A237271, A237593.

(* The d-th element in list minDiv[n, b] is the smallest numbers k<=n with exactly d<=b divisors, otherwise it is zero. Computation stops as soon as either inequality fails. *)
minDiv[n_, b_] :=
Module[{list = Array[0 &, b], k = 1, d},
  While[k <= n, d = DivisorSigma[0, k];
   If[d <= b && list[[d]] == 0, list[[d]] = k];
   If[d <= b, k++, k = n + 2]]; list]
a256259[n_, b_] :=
Map[DivisorSigma[1, #] &, Sort[Select[minDiv[n, b], # != 0 &]]]
a256259[100000, 300] (* computes the first 60 elements of the sequence *)
(* Hartmut F. W. Hoft, Apr 27 2015 *)

a(n) = A000203(A007416(n)).

A182941 a(n) = sum of divisors of A094348(n).

Original entry on oeis.org

1, 3, 7, 12, 28, 60, 91, 124, 168, 195, 360, 546, 744, 1170, 1344, 2418, 2880, 4368, 5952, 9360, 19344, 28800, 39312, 59520, 79248, 99944, 112320, 120960, 180048, 203112, 232128, 345600, 471744, 714240, 950976, 1199328, 1451520, 1572480, 2160576, 2437344, 2926080

Offset: 1

Peter Luschny, Jan 03 2011

nonn

a(10) = 195 is the first term which is neither in A007626 nor in A063072.

Cf. A000203, A094348, A007626, A063072.

seq(numtheory[sigma](A094348[i]),i=1..42);

a(n) = A000203(A094348(n)). - Omar E. Pol, Dec 08 2019

a(37)-a(41) from Jinyuan Wang, Mar 02 2020

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A007626 Sum of divisors of superabundant numbers (A004394).

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A256259 Sum of divisors of the minimal numbers (A007416).

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A182941 a(n) = sum of divisors of A094348(n).

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