A062832 - OEIS

%I #23 Nov 02 2023 04:22:05

%S 3,5,6,8,11,17,18,29,33,40,41,50,54,55,59,71,85,91,93,101,102,107,123,

%T 128,136,137,141,143,149,152,159,179,182,183,184,185,191,197,198,201,

%U 203,213,215,217,219,227,230,235,239,242,243,246,247,248,265,269,281

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

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

%H Giovanni Resta, <a href="/A062832/b062832.txt">Table of n, a(n) for n = 1..10000</a> (first 1000 terms from T. D. Noe)

%t Select[Range[300],DivisorSigma[0,#]==DivisorSigma[0,#+2]&] (* _Harvey P. Dale_, Mar 01 2012 *)

%t Position[Partition[DivisorSigma[0,Range[300]],3,1],_?(#[[1]]==#[[3]]&)]// Flatten//Quiet (* _Harvey P. Dale_, Mar 17 2017 *)

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

%Y Equals A067888 - 1. - _Michel Marcus_, Feb 11 2018

%K nonn

%O 1,1

%A _Jason Earls_, Jul 20 2001