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A199317
a(n) = 2*6^n + 1.
1
3, 13, 73, 433, 2593, 15553, 93313, 559873, 3359233, 20155393, 120932353, 725594113, 4353564673, 26121388033, 156728328193, 940369969153, 5642219814913, 33853318889473, 203119913336833, 1218719480020993, 7312316880125953, 43873901280755713
OFFSET
0,1
FORMULA
a(n) = 6*a(n-1)-5.
a(n) = 7*a(n-1)-6*a(n-2).
G.f.: (3-8*x)/((1-x)*(1-6*x)).
a(n) = 1 + A167747(n+1) = 1 + 2*A000400(n) = A000400(n) + A062394(n). - Alois P. Heinz, Jul 02 2023
MATHEMATICA
2 6^Range[0, 30]+1 (* or *) LinearRecurrence[{7, -6}, {3, 13}, 30] (* Harvey P. Dale, Jul 02 2023 *)
PROG
(Magma) [2*6^n+1: n in [0..30]];
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 05 2011
STATUS
approved