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A007486 a(n) = a(n-1)+a(n-2)+a(n-3).
(Formerly M2351)
+0
1
1, 3, 4, 8, 15, 27, 50, 92, 169, 311, 572, 1052, 1935, 3559, 6546, 12040, 22145, 40731, 74916, 137792, 253439, 466147, 857378, 1576964, 2900489, 5334831, 9812284, 18047604, 33194719, 61054607, 112296930, 206546256 (list; graph; listen)
OFFSET

1,2

COMMENT

If A001590 is the Tribonacci series, this might be called the Trucas series after the Lucas series A000032. - Paul Wayper (paulway(AT)mabula.net), Nov 28 2007

REFERENCES

N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

FORMULA

O.g.f.: x(1+2x)/(1-x-x^2-x^3). a(n)=A001590(n)+3*A000073(n). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 22 2008]

CROSSREFS

Cf. A001590, A000032, A000045.

Sequence in context: A104370 A033854 A042981 this_sequence A027977 A165438 A049894

Adjacent sequences: A007483 A007484 A007485 this_sequence A007487 A007488 A007489

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com).

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Last modified December 4 15:11 EST 2009. Contains 170347 sequences.


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