OFFSET
1,1
COMMENTS
Granville and Zhu show that the density of these numbers is 1/8.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
Andrew Granville and Yiliang Zhu, Representing binomial coefficients as sums of squares, Amer. Math. Monthly, Vol. 97, No. 6 (1990), pp. 486-493; alternative link.
MATHEMATICA
NoRepAs3Sqrs[n_] := Module[{e2}, e2=IntegerExponent[n, 2]; If[EvenQ[e2], 7==Mod[n/2^e2, 8], False]]; Select[Range[500], NoRepAs3Sqrs[Binomial[2#, # ]]&]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Oct 18 2004
STATUS
approved