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URL: https://oeis.org/A140498

⇱ A140498 - OEIS

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A140498
a(n) = 3*a(n-1)-3*a(n-2)+3*a(n-3) with a(0)=1, a(1)=3, a(2)=7.
0
1, 3, 7, 15, 33, 75, 171, 387, 873, 1971, 4455, 10071, 22761, 51435, 116235, 262683, 593649, 1341603, 3031911, 6851871, 15484689, 34994187, 79084107, 178723827, 403901721, 912786003, 2062824327, 4661820135, 10535345433, 23809048875, 53806570731, 121598601867
OFFSET
0,2
COMMENTS
Second differences of A137256.
FORMULA
G.f.: (1+x^2)/(1-3*x+3*x^2-3*x^3). - Colin Barker, Mar 28 2012
MATHEMATICA
LinearRecurrence[{3, -3, 3}, {1, 3, 7}, 32] (* or *) CoefficientList[Series[(1+x^2)/(1-3*x+3*x^2-3*x^3), {x, 0, 31}], x] (* James C. McMahon, Jul 11 2025 *)
PROG
(Magma) m:=32; R<x>:=PowerSeriesRing(Integers(), m); Coefficients(R!((1+x^2)/(1-3*x+3*x^2-3*x^3))); // Bruno Berselli, Mar 28 2012
CROSSREFS
Cf. A137256.
Sequence in context: A193641 A026701 A249512 * A136029 A225338 A101892
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Jun 29 2008
EXTENSIONS
More terms from Colin Barker, Mar 28 2012
STATUS
approved