OFFSET
1,1
COMMENTS
It is conjectured that 5282 positive numbers are not the sum of three 9-gonal numbers.
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, D3.
LINKS
T. D. Noe, Table of n, a(n) for n = 1..5282
R. K. Guy, Every number is expressible as the sum of how many polygonal numbers?, Amer. Math. Monthly 101 (1994), 169-172.
MATHEMATICA
nn = 700; non = Table[n*(7*n - 5)/2, {n, 0, nn}]; t = Table[0, {non[[-1]]}]; Do[n = non[[i]] + non[[j]] + non[[k]]; If[n <= non[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]
CROSSREFS
KEYWORD
nonn,fini
AUTHOR
T. D. Noe, Jul 16 2012
STATUS
approved