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a(n) = Sum_{k=0..n} (-1)^k*A001595(k)^2.
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%I #8 Aug 18 2024 20:29:34

%S 1,0,9,-16,65,-160,465,-1216,3273,-8608,22721,-59648,156577,-410432,

%T 1075529,-2817200,7378049,-19319840,50586481,-132447360,346768521,

%U -907878720,2376901249,-6222878976,16291823425,-42652732800,111666604425,-292347451216,765376349633,-2003782568608

%N a(n) = Sum_{k=0..n} (-1)^k*A001595(k)^2.

%H Sergio Falcon, <a href="https://doi.org/10.20944/preprints202408.1150.v1">Sum of the Squares of the Extended (k, t)-Fibonacci Numbers</a>, Preprints 2024, 2024081150. See p. 7.

%H <a href="/index/Rec#order_07">Index entries for linear recurrences with constant coefficients</a>, signature (-3,2,8,-2,-6,1,1).

%F a(n) = 4*(-1)^n*(2*Fibonacci(2*n)/5 + Fibonacci(n)^2 - Fibonacci(n)) + 8*n/5 + A059841(n) (see Falcon).

%F G.f.: (1 + 3*x + 7*x^2 + 3*x^3 + x^4 + x^5)/((1 - x)^2*(1 + x)*(1 + 3*x + x^2)*(1 + x - x^2)).

%t a[n_]:=4*(-1)^n*(2*Fibonacci[2*n]/5+Fibonacci[n]^2-Fibonacci[n])+8*n/5+(1+(-1)^n)/2; Array[a,30,0]

%Y Cf. A000045, A001595, A059841, A375500.

%K sign,easy

%O 0,3

%A _Stefano Spezia_, Aug 18 2024