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A199557
10*8^n+1.
1
11, 81, 641, 5121, 40961, 327681, 2621441, 20971521, 167772161, 1342177281, 10737418241, 85899345921, 687194767361, 5497558138881, 43980465111041, 351843720888321, 2814749767106561, 22517998136852481, 180143985094819841
OFFSET
0,1
FORMULA
a(n) = 8*a(n-1)-7.
a(n) = 9*a(n-1)-8*a(n-2).
G.f.: (11-18*x)/((1-x)*(1-8*x)).
PROG
(Magma) [10*8^n+1: n in [0..30]];
CROSSREFS
Sequence in context: A055429 A227556 A181989 * A003730 A334340 A335332
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 08 2011
STATUS
approved