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A048496
a(n) = 2^(n-1)*(3*n-4) + 3.
3
1, 2, 7, 23, 67, 179, 451, 1091, 2563, 5891, 13315, 29699, 65539, 143363, 311299, 671747, 1441795, 3080195, 6553603, 13893635, 29360131, 61865987, 130023427, 272629763, 570425347, 1191182339, 2483027971, 5167382531
OFFSET
0,2
COMMENTS
a(n) = T(2, n), array T given by A048494.
FORMULA
a(n) = A027992(n-1) + 1 = A053565(n) + 3.
From R. J. Mathar, Oct 31 2008: (Start)
a(n) = 5*a(n-1) - 8*a(n-2) + 4*a(n-3).
G.f.: (1 - 3*x + 5*x^2)/((1-x)(1-2*x)^2). (End)
PROG
(Magma) [2^(n-1)*(3*n-4)+3 : n in [0..30]]; // Vincenzo Librandi, Sep 26 2011
CROSSREFS
n-th difference of a(n), a(n-1), ..., a(0) is (1, 4, 7, 10, ...).
Sequence in context: A010748 A272819 A185250 * A369840 A210581 A037488
KEYWORD
nonn,easy
EXTENSIONS
Formula from Ralf Stephan, Jan 15 2004
STATUS
approved