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A023548
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Convolution of natural numbers >= 2 and Fibonacci numbers.
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15
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2, 5, 11, 21, 38, 66, 112, 187, 309, 507, 828, 1348, 2190, 3553, 5759, 9329, 15106, 24454, 39580, 64055, 103657, 167735, 271416, 439176, 710618, 1149821, 1860467, 3010317, 4870814, 7881162, 12752008, 20633203, 33385245, 54018483, 87403764, 141422284
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OFFSET
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1,1
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COMMENTS
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Minimal cost of maximum height Huffman tree of size n for strictly "worst case height" sequences. (A strictly "worst case height" sequence generates only maximum height Huffman trees; a non-strictly "worst case height" sequence can generate also non-maximum height Huffman trees.) - Alex Vinokur (alexvn(AT)barak-online.net), Oct 26 2004
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LINKS
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FORMULA
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Convolution of natural numbers n >= 1 with Lucas numbers (A000032).
a(n) = 4*(F(n+1) - 1) + 3*F(n) - n, F(n)=A000045 (Fibonacci).
G.f.: x*(2-x)/((1-x-x^2)*(1-x)^2). (End)
For n >= 1, a(n) = L(n+3) - (n+4), where L(n) are Lucas numbers. - Mario Catalani (mario.catalani(AT)unito.it), Jul 22 2004
a(n) = Fib(n+3) + F(n+1) - (n+3) for n > 1. - Alex Vinokur (alexvn(AT)barak-online.net), Oct 26 2004
a(n) = (-4 + (2^(-n)*((1-sqrt(5))^n*(-5+2*sqrt(5)) + (1+sqrt(5))^n*(5+2*sqrt(5)))) / sqrt(5) - n). - Colin Barker, Mar 11 2017
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MATHEMATICA
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Table[4(Fibonacci[n+1] -1) +3Fibonacci[n] -n, {n, 40}] (* Vincenzo Librandi, Sep 16 2017 *)
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PROG
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(PARI) a(n) = 4*fibonacci(n+1) + 3*fibonacci(n) - n - 4; \\ Michel Marcus, Sep 08 2016
(PARI) Vec(x*(2-x) / ((1-x-x^2)*(1-x)^2) + O(x^40)) \\ Colin Barker, Mar 11 2017
(Magma) [4*(Fibonacci(n+1)-1)+3*Fibonacci(n)-n: n in [1..40]]; // Vincenzo Librandi, Sep 16 2017
(Sage) [lucas_number2(n+3, 1, -1) -n-4 for n in (1..40)] # G. C. Greubel, Jul 08 2019
(GAP) List([1..40], n-> Lucas(1, -1, n+3)[2] -n-4) # G. C. Greubel, Jul 08 2019
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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