OFFSET
1,1
COMMENTS
a(k) is a term of A075039 iff a(k)+1 = a(k+1).
If a prime divides a(n) then it does not divide a(n) + 1. If a prime divides a(n) + 1, then it does not divide a(n). The sets of prime divisors of a(n) and a(n) + 1 are disjoint. - Torlach Rush, Jan 13 2018
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
EXAMPLE
230 = 2*5*23 and 230+1 = 3*7*11, therefore 230 is a term.
MATHEMATICA
Select[Range[2, 634], SquareFreeQ[#] && SquareFreeQ[# + 1] && Length[FactorInteger[#]] == Length[FactorInteger[# + 1]] &] (* T. D. Noe, Jun 26 2013 *)
#[[1, 1]]&/@Select[Partition[Table[{n, If[SquareFreeQ[n], 1, 0], PrimeOmega[ n]}, {n, 700}], 2, 1], #[[1, 2]]==#[[2, 2]]==1&&#[[1, 3]]==#[[2, 3]]&] (* Harvey P. Dale, Dec 13 2014 *)
PROG
(PARI) for(n=1, 10^3, if ( issquarefree(n) && issquarefree(n+1) && (omega(n)==omega(n+1)) , print1(n, ", "))); \\ Joerg Arndt, Jun 26 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jul 14 2003
STATUS
approved