

A038508


Expansion of (12*xx^2)/((12*x)*(12*x+2*x^2)).


2



1, 2, 5, 12, 30, 76, 196, 512, 1352, 3600, 9648, 25984, 70240, 190400, 517184, 1406976, 3831936, 10445056, 28488448, 77735936, 212186624, 579320832, 1581966336, 4320477184, 11800692736, 32233951232
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OFFSET

0,2


COMMENTS

Number of (s(0), s(1), ..., s(n+1)) such that 0 < s(i) < 6 and s(i)  s(i1) <= 1 for i = 1,2,....,n+1, s(0) = 1, s(n+1) = 2.  Herbert Kociemba, Jun 17 2004


LINKS

Table of n, a(n) for n=0..25.
Index entries for linear recurrences with constant coefficients, signature (4,2,4).


FORMULA

a(n)=(3*2^(n+1)  Sqrt[3](1Sqrt[3])^(n+1) + Sqrt[3](1+Sqrt[3])^(n+1))/12  Herbert Kociemba, Jun 17 2004
2*a(n) = 2^n + A002605(n+1).  R. J. Mathar, Sep 11 2019


PROG

(PARI) Vec((12*xx^2)/(14*x+2*x^2+4*x^3)+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012


CROSSREFS

First differences are in A094297.
Sequence in context: A108360 A051163 A051450 * A105695 A244884 A002026
Adjacent sequences: A038505 A038506 A038507 * A038509 A038510 A038511


KEYWORD

nonn,easy


AUTHOR

N. J. A. Sloane.


STATUS

approved



