A118367 Largest number that is not the sum of five n-gonal numbers.

0, 0, 0, 26, 47, 188, 245, 343, 494, 821, 901, 1283, 1729, 1972, 2715, 3795, 4030, 4788, 5681, 6379, 6948, 9484, 9913, 10342, 10771, 14064, 15035, 19182, 19865, 20548, 27315, 28194, 29073, 29952, 33351, 34302, 35253, 50772, 52106, 53440, 54774

Offset

3,4

Comments

Legendre proved that a number N is the sum of five n-gonal numbers if N >= 28(n-2)^3. For odd n, four n-gonal numbers are enough. See A118368.

References

Melvyn B. Nathanson, Additive number theory: the classical bases, Springer, 1996.

Links

Table of n, a(n) for n=3..43.

R. K. Guy, Every number is expressible as the sum of how many polygonal numbers?, Amer. Math. Monthly 101 (1994), 169-172.

Eric Weisstein's World of Mathematics, Polygonal Number

Crossrefs

Cf. A118368.

Sequence in context: A039458 A291672 A159651 * A316120 A261932 A364025

Adjacent sequences: A118364 A118365 A118366 * A118368 A118369 A118370

Keyword

nonn

Author

T. D. Noe, Apr 25 2006

Status

approved