OFFSET
1,7
COMMENTS
LINKS
T. D. Noe, Table of n, a(n) for n=1..10000
L. Hodges, A lesser-known Goldbach conjecture, Math. Mag., 66 (1993), 45-47.
EXAMPLE
a(11)=3 because 21 = 19+2*1^2 = 13+2*2^2 = 3+2*3^2.
MATHEMATICA
Table[cnt=0; Do[If[PrimeQ[n-2*k^2], cnt++ ], {k, Floor[Sqrt[n/2]]}]; cnt, {n, 1, 20000, 2}]
CROSSREFS
KEYWORD
nonn
AUTHOR
T. D. Noe, Aug 23 2008
STATUS
approved