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A072335 Expansion of 1/((1-x^2)*(1-4*x+x^2)). +0
2
1, 4, 16, 60, 225, 840, 3136, 11704, 43681, 163020, 608400, 2270580, 8473921, 31625104, 118026496, 440480880, 1643897025, 6135107220, 22896531856, 85451020204, 318907548961, 1190179175640, 4441809153600, 16577057438760, 61866420601441, 230888624967004 (list; graph; listen)
OFFSET

0,2

LINKS

N. J. A. Sloane, Transforms

Index entries for sequences related to Chebyshev polynomials.

FORMULA

a(n) = 1/12*((7-4*sqrt(3))*(2-sqrt(3))^n+(7+4*sqrt(3))*(2+sqrt(3))^n-3+(-1)^n). Recurrence: a(n) = 4*a(n-1)-4*a(n-3)+a(n-4).

a(n)=sum{k=0..floor(n/2), U(n-2k, 2)} - Paul Barry (pbarry(AT)wit.ie), Nov 15 2003

CROSSREFS

EULER transform of A072279 (with its initial 1 omitted).

A001353(n)^2 is a bisection of a(n).

Sequence in context: A089932 A120926 A128650 this_sequence A081161 A032106 A047097

Adjacent sequences: A072332 A072333 A072334 this_sequence A072336 A072337 A072338

KEYWORD

nonn

AUTHOR

N. J. A. Sloane (njas(AT)research.att.com), Jul 15 2002

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Last modified December 13 23:45 EST 2009. Contains 170824 sequences.


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