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A214421 Numbers not representable as the sum of three 12-gonal numbers. 2
4, 5, 6, 7, 8, 9, 10, 11, 15, 16, 17, 18, 19, 20, 21, 22, 23, 26, 27, 28, 29, 30, 31, 32, 37, 38, 39, 40, 41, 42, 43, 44, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 58, 59, 60, 61, 62, 63, 68, 69, 70, 71, 72, 73, 74, 75, 79, 80, 81, 82, 83, 84, 85, 86, 87, 89 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
There are an infinite number of numbers that are not the sum of three 12-gonal numbers.
REFERENCES
R. K. Guy, Unsolved Problems in Number Theory, D3.
LINKS
R. K. Guy, Every number is expressible as the sum of how many polygonal numbers?, Amer. Math. Monthly 101 (1994), 169-172.
MATHEMATICA
nn = 100; dod = Table[n*(5n-4), {n, 0, nn}]; t = Table[0, {dod[[-1]]}]; Do[n = dod[[i]] + dod[[j]] + dod[[k]]; If[n <= dod[[-1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]
CROSSREFS
Cf. A051624 (12-gonal numbers).
Sequence in context: A194283 A299546 A039128 * A294237 A162706 A088331
KEYWORD
nonn
AUTHOR
T. D. Noe, Jul 17 2012
STATUS
approved

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Last modified March 29 02:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)