OFFSET
1,3
COMMENTS
The squares may be zero.
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
EXAMPLE
MAPLE
filter:= proc(n)
andmap(t -> (t[1] mod 4 <> 3 or t[2]::even), ifactors(n)[2])
end proc:
select(filter, [seq(i*(i+1)/2, i=0..500)]); # Robert Israel, Nov 22 2017
MATHEMATICA
t = Range[0, 250]^2; t1 = Flatten[Table[a + b, {a, t}, {b, t}]]; t2 = Accumulate[Range[300]]; Intersection[t1, t2] (* Jayanta Basu, Jul 03 2013 *)
Select[Union[Total/@Tuples[Range[0, 300]^2, 2]], OddQ[Sqrt[8#+1]]&] (* Harvey P. Dale, Apr 22 2015 *)
PROG
(Python)
from itertools import count, islice
from sympy import factorint
def A073613_gen(): # generator of terms
return filter(lambda n:all(p & 3 != 3 or e & 1 == 0 for p, e in factorint(n).items()), (m*(m+1)//2 for m in count(0)))
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Jason Earls, Aug 29 2002
EXTENSIONS
Edited and initial 0 added by M. F. Hasler, Nov 20 2017
STATUS
approved