OFFSET
1,1
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
42 is there because it's (4*5+1)*2^1 and is not a sum of two squares.
MAPLE
filter:= proc(n) local w; w:= n/2^padic:-ordp(n, 2);
w mod 4 = 1 and select(t -> t[2]::odd and t[1] mod 4 = 3, ifactors(w)[2]) <> []
end proc:
select(filter, [$1..1000]); # Robert Israel, Oct 28 2018
MATHEMATICA
okQ[n_] := EvenQ[(n/2^IntegerExponent[n, 2]-1)/2] && SquaresR[2, n] == 0;
Select[Range[1000], okQ] (* Jean-François Alcover, Feb 09 2023 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Alford Arnold, Jun 03 2006
EXTENSIONS
More terms from Don Reble, Jul 24 2006
STATUS
approved