A231090 Initial members of abundant sextuplets, i.e., values of n such that (n, n+2, n+4, n+6, n+8, n+10) are all abundant numbers.

801340, 962650, 7353340, 21964300, 41642140, 48049690, 55455940, 89034940, 89851450, 92253850, 105259540, 107948380, 109455340, 114295450, 116754940, 122349370, 135575980, 156009850, 159521050, 173645440, 188586700, 192674170, 193137850, 220301770, 221355126

Offset

1,1

Links

Shyam Sunder Gupta and Donovan Johnson, Table of n, a(n) for n = 1..5000 (first 126 terms from Shyam Sunder Gupta)

Example

801340, 801342, 801344, 801346, 801348, 801350 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 > 5, AppendTo[a, n - 10]], m = 0], {n, 2, 1000000000, 2}]; a
2*SequencePosition[Table[If[DivisorSigma[1, n]>2n, 1, 0], {n, 2, 2214*10^5, 2}], {1, 1, 1, 1, 1, 1}][[All, 1]] (* Harvey P. Dale, May 12 2022 *)

Prog

(PARI) is(n)=sigma(n, -1)>2 && sigma(n+2, -1)>2 && sigma(n+4, -1)>2 && sigma(n+6, -1)>2 && sigma(n+8, -1)>2 && sigma(n+10, -1)>2 \\ Charles R Greathouse IV, Feb 21 2017

Crossrefs

Cf. A005101, A108926, A231086, A231088, A231089, A231092, A231093.

Sequence in context: A112451 A235006 A231629 * A237298 A069338 A224657

Adjacent sequences: A231087 A231088 A231089 * A231091 A231092 A231093

Keyword

nonn

Author

Shyam Sunder Gupta, Nov 03 2013

Status

approved