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 A203169 Sum of the fourth powers of the first n even-indexed Fibonacci numbers. 3
 0, 1, 82, 4178, 198659, 9349284, 439330980, 20639983621, 969645224182, 45552722051318, 2140008541351943, 100534850436141384, 4722997973709689160, 221880369994471370761, 10423654392318557192602, 489689876072761951752602 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,3 COMMENTS Natural bilateral extension (brackets mark index 0): ..., -9349284, -198659, -4178, -82, -1, 0, [0], 1, 82, 4178, 198659, 9349284, ...  That is, a(-n) = -a(n-1). LINKS Index entries for linear recurrences with constant coefficients, signature (56,-440,770,-440,56,-1). FORMULA Let F(n) be the Fibonacci number A000045(n). a(n) = sum_{k=1..n} F(2k)^4. Closed form: a(n) = (1/75)(F(8n+4) - 12 F(4n+2) + 9(2 n + 1)). Recurrence: a(n) - 56 a(n-1) + 440 a(n-2) - 770 a(n-3) + 440 a(n-4) - 56 a(n-5) + a(n-6) = 0. G.f.: A(x) = (x + 26 x^2 + 26 x^3 + x^4)/(1 - 56 x + 440 x^2 - 770 x^3 + 440 x^4 - 56 x^5 + x^6) = x(1 + x)(1 + 25 x + x^2)/((1 - x)^2 (1 - 7 x + x^2)(1 - 47 x + x^2)). MATHEMATICA a[n_Integer] := (1/75)(Fibonacci[8n+4] - 12*Fibonacci[4n+2] + 9*(2*n+1)); Table[a[n], {n, 0, 20}] CROSSREFS Cf. A203170, A203171, A203172. Cf. A027941, A103434, A163198. Sequence in context: A035736 A017745 A217676 * A214815 A280959 A252705 Adjacent sequences:  A203166 A203167 A203168 * A203170 A203171 A203172 KEYWORD nonn,easy AUTHOR Stuart Clary, Dec 30 2011 STATUS approved

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Last modified December 10 04:15 EST 2019. Contains 329885 sequences. (Running on oeis4.)