

A322039


Expansion of (1 + x)^2 / ((1  x)^2*(1 + 2*x)^2).


2



1, 0, 4, 4, 16, 28, 72, 148, 336, 716, 1560, 3332, 7136, 15164, 32168, 67956, 143216, 300972, 631096, 1320420, 2757376, 5747740, 11961544, 24855124, 51574416, 106877068, 221210712, 457334468, 944495136, 1948642556
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OFFSET

0,3


COMMENTS

Connected with tiling of torus by squares (see A322038).


LINKS

Colin Barker, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (2,3,4,4).


FORMULA

From Colin Barker, Dec 04 2018: (Start)
a(n) = 2*a(n1) + 3*a(n2) + 4*a(n3)  4*a(n4) for n>3.
a(n) = (16 + 11*(2)^n + 3*(4+(2)^n)*n) / 27.
(End)


MATHEMATICA

LinearRecurrence[{2, 3, 4, 4}, {1, 0, 4, 4}, 100] (* Amiram Eldar, Dec 04 2018 *)


PROG

(PARI) Vec((1 + x)^2 / ((1  x)^2*(1 + 2*x)^2) + O(x^40)) \\ Colin Barker, Dec 04 2018


CROSSREFS

Cf. A322038, A322040.
Sequence in context: A092959 A330054 A183433 * A158101 A038234 A099462
Adjacent sequences: A322036 A322037 A322038 * A322040 A322041 A322042


KEYWORD

sign,easy


AUTHOR

N. J. A. Sloane, Dec 03 2018


STATUS

approved



