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A198796
3*6^n-1.
2
2, 17, 107, 647, 3887, 23327, 139967, 839807, 5038847, 30233087, 181398527, 1088391167, 6530347007, 39182082047, 235092492287, 1410554953727, 8463329722367, 50779978334207, 304679870005247, 1828079220031487
OFFSET
0,1
FORMULA
a(n) = 6*a(n-1)+5. a(n) = 7*a(n-1)-6*a(n-2), n>1.
G.f.: ( 2+3*x ) / ( (6*x-1)*(x-1) ). - R. J. Mathar, Oct 30 2011
MATHEMATICA
Table[3*6^n-1, {n, 0, 30}] (* or *) LinearRecurrence[{7, -6}, {2, 17}, 30] (* Harvey P. Dale, May 22 2016 *)
PROG
(Magma) [3*6^n-1: n in [0..30]]
CROSSREFS
Sequence in context: A213787 A105652 A204238 * A186104 A155845 A115354
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 30 2011
STATUS
approved