OFFSET
1,1
COMMENTS
Complement of the union of {1} and A072587. - Reinhard Zumkeller, Nov 15 2012, corrected version from Jun 23 2002
A036537 is a subsequence and this sequence is a subsequence of A162644. - Reinhard Zumkeller, Jul 08 2009
The asymptotic density of this sequence is A065463. - Amiram Eldar, Sep 18 2022
REFERENCES
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
LINKS
T. D. Noe, Table of n, a(n) for n = 1..1000
Eckford Cohen, Quadratic congruences with an odd number of summands, Amer. Math. Monthly, 73 (1966), 138-143.
MAPLE
isA002035 := proc(n)
local pe;
for pe in ifactors(n)[2] do
if type(pe[2], 'even') then
return false;
end if;
end do:
true ;
end proc:
A002035 := proc(n)
option remember;
if n =1 then
2;
else
for a from procname(n-1)+1 do
if isA002035(a) then
return a;
end if;
end do:
end if;
end proc:
seq(A002035(n), n=1..100) ; # R. J. Mathar, Nov 27 2017
MATHEMATICA
ok[n_] := And @@ OddQ /@ FactorInteger[n][[All, 2]];
Select[Range[2, 101], ok]
(* Jean-François Alcover, Apr 22 2011 *)
Select[Range[2, 110], AllTrue[FactorInteger[#][[All, 2]], OddQ]&] (* Harvey P. Dale, Nov 02 2022 *)
PROG
(Haskell)
a002035 n = a002035_list !! (n-1)
a002035_list = filter (all odd . a124010_row) [1..]
-- Reinhard Zumkeller, Nov 14 2012
(PARI) is(n)=Set(factor(n)[, 2]%2)==[1] \\ Charles R Greathouse IV, Feb 07 2017
CROSSREFS
KEYWORD
nonn,nice
AUTHOR
EXTENSIONS
More terms from Reinhard Zumkeller, Jun 23 2002
STATUS
approved