Numbers that are not the sum of 3 generalized 17-gonal numbers.
4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 20, 21, 22, 23, 24, 25, 26, 27, 30, 33, 36, 37, 38, 39, 40, 41, 46, 47, 52, 53, 54, 55, 56, 59, 64, 67, 68, 69, 70, 72, 73, 75, 78, 80, 81, 83, 84, 85, 90, 93, 98, 99, 106, 107, 114, 116, 117, 119, 120, 123, 124, 126, 127, 132
1
It appears that 75150 is the last number not representable as the sum of 3 generalized 17-gonal numbers.
T. D. Noe, Plot of 641 terms
T. D. Noe, Table of 641 terms
Eric W. Weisstein, MathWorld: Polygonal Number
(Mma) f = 17; nn = 200; t = Table[k ((f - 2) k - (f - 4))/2, {k, -nn, nn}]; t2 = Select[Union[Flatten[Table[a + b + c, {a, t}, {b, t}, {c, t}]]], # <= t[[-1]] &]; Complement[Range[t[[-1]]], t2]
nonn,fini
T. D. Noe, Dec 28 2015