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A199111
a(n) = 8*3^n+1.
3
9, 25, 73, 217, 649, 1945, 5833, 17497, 52489, 157465, 472393, 1417177, 4251529, 12754585, 38263753, 114791257, 344373769, 1033121305, 3099363913, 9298091737, 27894275209, 83682825625, 251048476873, 753145430617, 2259436291849, 6778308875545
OFFSET
0,1
FORMULA
a(n) = 3*a(n-1)-2.
a(n) = 4*a(n-1)-3*a(n-2).
G.f.: (9-11*x)/((1-x)*(1-3*x)). - Bruno Berselli, Nov 03 2011
a(n) = 1 + 8*A000244(n) = 1 + A005051(n). - Omar E. Pol, Nov 18 2011
PROG
(Magma) [8*3^n+1: n in [0..30]];
CROSSREFS
Cf. A000244, A005051, A160173. - Omar E. Pol, Nov 18 2011
Sequence in context: A126363 A036836 A125997 * A196350 A196353 A166103
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Nov 03 2011
STATUS
approved