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A231088 Initial members of abundant triples, i.e., values of n such that (n, n+2, n+4) are all abundant numbers. 8
100, 196, 220, 304, 348, 350, 364, 460, 616, 640, 700, 736, 832, 1036, 1060, 1144, 1180, 1216, 1312, 1372, 1456, 1480, 1660, 1696, 1876, 1900, 1936, 1984, 1998, 2000, 2020, 2176, 2208, 2210, 2296, 2320, 2548, 2620, 2716, 2740, 2748, 2750, 2988, 2990, 2992 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Shyam Sunder Gupta, Table of n, a(n) for n = 1..5000

EXAMPLE

100, 102, 104 are abundant, thus the smallest number is listed.

MATHEMATICA

AbundantQ[n_] := DivisorSigma[1, n] > 2n; m = 0; a = {}; Do[If[AbundantQ[n], m = m + 1; If[m > 2, AppendTo[a, n - 4]], m = 0], {n, 2, 1000000, 2}]; a

2*Flatten[Position[Partition[Table[If[DivisorSigma[1, n]>2n, 1, 0], {n, 2, 3000, 2}], 3, 1], {1, 1, 1}]] (* Harvey P. Dale, Aug 19 2014 *)

PROG

(PARI) is(n)=sigma(n, -1)>2 && sigma(n+2, -1)>2 && sigma(n+4, -1)>2 \\ Charles R Greathouse IV, Feb 21 2017

CROSSREFS

Cf. A005101, A108926, A231086, A231089, A231090, A231092, A231093.

Sequence in context: A025411 A025408 A068805 * A104023 A072367 A172178

Adjacent sequences:  A231085 A231086 A231087 * A231089 A231090 A231091

KEYWORD

nonn

AUTHOR

Shyam Sunder Gupta, Nov 03 2013

STATUS

approved

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Last modified February 27 19:23 EST 2020. Contains 332308 sequences. (Running on oeis4.)