OFFSET
1,1
FORMULA
a(n)=A007501(n). [From R. J. Mathar, Sep 04 2008]
MATHEMATICA
f[n_] := n(n + 1)/2; Table[ Nest[f, 2, n], {n, 10}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Robert G. Wilson v, Jul 02 2004
STATUS
approved