A096662 Least nontrivial n-tuply triangular number.

3, 6, 21, 231, 26796, 359026206, 64449908476890321, 2076895351339769460477611370186681, 2156747150208372213435450937462082366919951682912789656986079991221

Offset: 1

Author

Robert G. Wilson v, Jul 02 2004

Keywords

• nonn

Crossrefs

Cf. A000217, A002817, A064322, A066370.

Programs

Mathematica

f[n_] := n(n + 1)/2; Table[ Nest[f, 2, n], {n, 10}]

Formula

a(n)=A007501(n). [From R. J. Mathar, Sep 04 2008]