A217740 Abundant numbers with abundant subscripts.

60, 84, 90, 104, 132, 160, 176, 186, 208, 228, 240, 260, 282, 304, 308, 336, 342, 354, 368, 378, 400, 416, 426, 438, 450, 464, 474, 498, 522, 546, 570, 576, 594, 618, 642, 654, 666, 696, 720, 728, 740, 762, 786, 804, 812, 820, 834, 852, 860, 882, 900, 910, 918

Offset

1,1

Comments

The abundant-index-of-abundant numbers, or "meta-abundant" numbers.

Subset of A005101.

Links

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

Example

The first abundant number is 12, so the first meta-abundant number is the 12th abundant number; A005101(A005101(1))=A005101(12)=60.

Mathematica

abQ[n_] := DivisorSigma[1, n] > 2 n; s = {}; c = 0; Do[If[abQ[n], c++; If[abQ[c], AppendTo[s, n]]], {n, 1, 1000}]; s (* Amiram Eldar, Jun 21 2019 *)

Crossrefs

Cf. A005101 (abundant numbers).

Cf. A006450 (primes with prime subscripts).

Sequence in context: A067207 A261375 A349758 * A375055 A123712 A178212

Adjacent sequences: A217737 A217738 A217739 * A217741 A217742 A217743

Keyword

nonn

Author

Kevin L. Schwartz and Christian N. K. Anderson, Mar 23 2013

Status

approved