OFFSET
0,2
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..27
FORMULA
a(n) = d^n * product(d^n - d^k, k=0..n-1).
MATHEMATICA
FoldList[ #1*20^#2 (20^#2-1)&, 1, Range[ 20 ] ]
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved