A062832 Numbers k such that k and k+2 have the same number of divisors.

3, 5, 6, 8, 11, 17, 18, 29, 33, 40, 41, 50, 54, 55, 59, 71, 85, 91, 93, 101, 102, 107, 123, 128, 136, 137, 141, 143, 149, 152, 159, 179, 182, 183, 184, 185, 191, 197, 198, 201, 203, 213, 215, 217, 219, 227, 230, 235, 239, 242, 243, 246, 247, 248, 265, 269, 281

Offset: 1

Author

Jason Earls, Jul 20 2001

Keywords

• nonn

Comments

The lesser member of every twin-prime pair occurs in this sequence. Hence A001359 is a subsequence. - T. D. Noe, Sep 17 2007

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)

Crossrefs

Equals A067888 - 1. - Michel Marcus, Feb 11 2018

Programs

Mathematica

Select[Range[300],DivisorSigma[0,#]==DivisorSigma[0,#+2]&] (* Harvey P. Dale, Mar 01 2012 *)
Position[Partition[DivisorSigma[0,Range[300]],3,1],?(#[[1]]==#[[3]]&)]// Flatten//Quiet (* _Harvey P. Dale, Mar 17 2017 *)

PARI

je=[]; for(n=1,1000,a=numdiv(n); b=numdiv(n+2); if(a==b,je=concat(je,n))); je