

A176965


a(n) = 2^(n1)  (2^n*(1)^n + 2)/3.


2



1, 0, 6, 2, 26, 10, 106, 42, 426, 170, 1706, 682, 6826, 2730, 27306, 10922, 109226, 43690, 436906, 174762, 1747626, 699050, 6990506, 2796202, 27962026, 11184810, 111848106, 44739242, 447392426, 178956970, 1789569706, 715827882, 7158278826
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OFFSET

1,3


COMMENTS

The ratio a(n+1)/a(n) approaches 10 for even n and 2/5 for odd n as n>infinity.


LINKS

Table of n, a(n) for n=1..33.
Index entries for linear recurrences with constant coefficients, signature (1,4,4).


FORMULA

From R. J. Mathar, Apr 30 2010: (Start)
a(n) = a(n1) + 4*a(n2)  4*a(n3).
G.f.: x*(1+2*x^2x) / ( (x1)*(2*x+1)*(2*x1) ). (End)
a(n) = A087231(n), n > 2.  R. J. Mathar, May 03 2010
a(2n1) = A061547(2n), a(2n) = A061547(2n1), n > 0.  Yosu Yurramendi, Dec 23 2016
a(n+1) = 2*A096773(n), n > 0.  Yosu Yurramendi, Dec 30 2016
a(2n1) = A020989(n1), a(2n) = A020988(n1), n > 0.  Yosu Yurramendi, Jan 03 2017
a(2n1) = (A083597(n1) + A000302(n1))/2, a(2n) = (A083597(n1)  A000302(n1))/2, n > 0.  Yosu Yurramendi, Mar 04 2017
a(n+2) = 4*a(n) + 2, a(1) = 1, a(2) = 0, n > 0.  Yosu Yurramendi, Mar 07 2017


MATHEMATICA

a[1] := 1;
a[n_] := a[n] = a[n  1]/2 +(1)^(n  1)*Sqrt[(5 + 4*(1)^(n  1))]/2:
Table[2^(n  1)*a[n], {n, 1, 30}]


CROSSREFS

Sequence in context: A036173 A142707 A305874 * A084249 A176591 A191703
Adjacent sequences: A176962 A176963 A176964 * A176966 A176967 A176968


KEYWORD

nonn,easy


AUTHOR

Roger L. Bagula, Apr 29 2010


STATUS

approved



