A165893 Numbers n with property that n(n+2)(n+4) is a triangular number.

0, 1, 3, 11, 30, 40, 122, 130, 1972

Offset: 1

Author

Zak Seidov, Sep 29 2009

Keywords

• nonn
• fini
• full

Comments

Abscissas of integral points on the elliptic curve: m^2 = 8*n^3 + 48*n^2 + 64*n + 1.

Crossrefs

Cf. A001219 Triangular numbers of form a(a+1)(a+2), A165892 Triangular numbers of form a(a+2)(a+4).

Programs

Mathematica

TNQ[n_]:=IntegerQ[Sqrt[1+8n]];Select[Range[7500],TNQ[ #(#+2)(#+4)]&]

Extensions

fini, full keywords from Max Alekseyev, Oct 01 2009

Initial 0 added by Zak Seidov, Oct 04 2009 at the suggestion of Alexander R. Povolotsky.