

A213523


Numbers not representable as the sum of three heptagonal numbers.


3



4, 5, 6, 10, 11, 12, 13, 16, 17, 22, 23, 24, 27, 28, 29, 30, 31, 33, 38, 39, 40, 44, 45, 46, 47, 49, 50, 51, 58, 60, 61, 64, 65, 66, 67, 71, 72, 76, 77, 78, 79, 84, 85, 87, 92, 93, 94, 97, 98, 101, 103, 104, 105, 108, 109, 118, 121, 124, 125, 127, 129, 132
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OFFSET

1,1


COMMENTS

It is conjectured that 1348 positive numbers are not the sum of three heptagonal numbers.


REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, D3.


LINKS

T. D. Noe, Table of n, a(n) for n = 1..1348
R. K. Guy, Every number is expressible as the sum of how many polygonal numbers?, Amer. Math. Monthly 101 (1994), 169172.


MATHEMATICA

nn = 350; hep = Table[n*(5*n3)/2, {n, 0, nn}]; t = Table[0, {hep[[1]]}]; Do[n = hep[[i]] + hep[[j]] + hep[[k]]; If[n <= hep[[1]], t[[n]] = 1], {i, nn}, {j, i, nn}, {k, j, nn}]; Flatten[Position[t, 0]]


CROSSREFS

Cf. A000566 (heptagonal numbers).
Cf. A118278, A118279.
Sequence in context: A144022 A028280 A120520 * A246441 A026312 A070751
Adjacent sequences: A213520 A213521 A213522 * A213524 A213525 A213526


KEYWORD

nonn,fini


AUTHOR

T. D. Noe, Jul 16 2012


STATUS

approved



