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A217740 Abundant numbers with abundant subscripts. 1
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 (list; graph; refs; listen; history; text; internal format)
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: A323979 A067207 A261375 * A123712 A178212 A182855

Adjacent sequences:  A217737 A217738 A217739 * A217741 A217742 A217743

KEYWORD

nonn

AUTHOR

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

STATUS

approved

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Last modified April 8 04:26 EDT 2020. Contains 333312 sequences. (Running on oeis4.)