A027696 Nonparametric solutions to problem in A027669: n such that for some m, the sum of the first m n-gonal numbers is again an n-gonal number.

3, 4, 6, 8, 10, 11, 14, 17, 30, 41, 43, 50, 60, 88, 145, 276, 322, 374, 823, 1152

Offset

0,1

Links

Table of n, a(n) for n=0..19.

Formula

The parametric solution: if n=2 mod 3, the sum of the first (n^2-4*n-2)/3 n-gonal numbers is the ((n^3-6*n^2+3*n+19)/9)-th n-gonal number.

Crossrefs

Cf. A027669.

Sequence in context: A184398 A024665 A027669 * A027440 A360637 A169866

Adjacent sequences: A027693 A027694 A027695 * A027697 A027698 A027699

Keyword

nonn,more

Author

Masanobu Kaneko (mkaneko(AT)math.kyushu-u.ac.jp)

Extensions

More terms from Masanobu Kaneko (mkaneko(AT)math.kyushu-u.ac.jp), Jan 05 1998

Status

approved