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A171665 Numbers n such that n and n+1 have same number of divisors, and that number of divisors is larger than 4. 2
44, 75, 98, 104, 116, 135, 147, 171, 189, 230, 231, 242, 243, 244, 285, 296, 332, 344, 374, 375, 387, 429, 434, 507, 548, 603, 604, 609, 645, 663, 664, 724, 735, 741, 776, 782, 805, 819, 844, 874, 902, 903, 908, 931, 963, 969, 986, 1001, 1015, 1022, 1029 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..2000

MATHEMATICA

f[n_]:=Length[Divisors[n]]; lst={}; Do[If[f[n]==f[n+1]&&f[n]>4, AppendTo[lst, n]], {n, 7!}]; lst

Position[Partition[DivisorSigma[0, Range[1100]], 2, 1], _?(#[[1]] == #[[2]]> 4&), {1}, Heads->False]//Flatten (* Harvey P. Dale, Sep 30 2016 *)

CROSSREFS

Cf. A005237

Sequence in context: A250329 A242515 A156812 * A049103 A074172 A039386

Adjacent sequences:  A171662 A171663 A171664 * A171666 A171667 A171668

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Dec 14 2009

STATUS

approved

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Last modified May 8 15:21 EDT 2021. Contains 343666 sequences. (Running on oeis4.)