OFFSET
1,2
LINKS
FORMULA
prod_{k=1}^{k=n} {(q^k - 1) / (q - 1)}
a(1) = 1, a(n) = (((-9)^n - 1) * a(n-1))/(-10). - Vincenzo Librandi, Oct 26 2012
MATHEMATICA
RecurrenceTable[{a[1]==1, a[n]==(((-9)^n - 1) * a[n-1])/(-10)}, a, {n, 15}] (* Vincenzo Librandi, Oct 26 2012 *)
PROG
(Magma) I:=[1]; [n le 1 select I[n] else (((-9)^n - 1) * Self(n-1))/(-10): n in [1..13]]; // Vincenzo Librandi, Oct 26 2012
CROSSREFS
KEYWORD
sign,easy
AUTHOR
STATUS
approved