|
%I #14 Feb 27 2019 01:19:42
%S 5,6,7,10,13,16,20,22,24,27,32,35,36,37,45,46,48,49,50,51,58,61,62,64,
%T 68,73,74,76,80,82,91,92,99,100,106,115,117,120,123,124,143,144,146,
%U 152,153,157,164,166,168,169,170,174,178,187,188,193,196,206,212,224,225
%N A positive integer k is included if |d(k+1) - d(k)| is a prime, where d(k) is the number of divisors of k.
%H Harvey P. Dale, <a href="/A162317/b162317.txt">Table of n, a(n) for n = 1..1000</a>
%e 24 is in the sequence because |d(25) - d(24)| = |3 - 8| = 5 is a prime. - _Emeric Deutsch_, Jul 12 2009
%p with(numtheory): a := proc (n) if isprime(abs(tau(n+1)-tau(n))) = true then n else end if end proc: seq(a(n), n = 1 .. 250); # _Emeric Deutsch_, Jul 12 2009
%t Flatten[Position[Partition[DivisorSigma[0,Range[250]],2,1],_?(PrimeQ[Abs[ First[#]-Last[#]]]&),{1},Heads->False]] (* _Harvey P. Dale_, May 26 2014 *)
%Y Cf. A051950.
%K nonn
%O 1,1
%A _Leroy Quet_, Jul 01 2009
%E Extended by _Emeric Deutsch_, Jul 12 2009
|
