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 A341928 a(n) = F(n+4) * F(n+2) + 7 * (-1)^n where F(n) = A000045(n) are the Fibonacci numbers. 1
 3, 31, 58, 175, 435, 1162, 3019, 7927, 20730, 54295, 142123, 372106, 974163, 2550415, 6677050, 17480767, 45765219, 119814922, 313679515, 821223655, 2149991418, 5628750631, 14736260443, 38580030730, 101003831715, 264431464447, 692290561594, 1812440220367 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS First differences of A341208. Second differences of A338225. Third differences of A226205 n > 2. Third differences between the areas of consecutive rectangles with side lengths F(n+3) and F(n). Twice the third differences between the areas of consecutive deltoids with cross lengths F(n+3) and F(n). Twice the third differences between the areas of consecutive triangles with the height and base length are F(n+3) and F(n). REFERENCES Burak Muslu, Sayılar ve Bağlantılar, Luna, 2021, p. 51 (in Turkish). LINKS Table of n, a(n) for n=1..28. Index entries for linear recurrences with constant coefficients, signature (2,2,-1). FORMULA a(n) = F(n+4) * F(n+2) + 7 * (-1)^n. G.f.: x*(3 + 25*x - 10*x^2)/(1 - 2*x - 2*x^2 + x^3). EXAMPLE For n = 2, a(2) = F(2+4) * F(2+2) + 7 * (-1)^2 = 8 * 3 + 7 = 31. MATHEMATICA Table[Fibonacci[n + 4] * Fibonacci[n + 2] + 7 * (-1)^n, {n, 1, 28}] (* Amiram Eldar, Feb 23 2021 *) PROG (PARI) a(n) = fibonacci(n+4)*fibonacci(n+2) + 7*(-1)^n; \\ Michel Marcus, Feb 23 2021 CROSSREFS Cf. A000045, A341208, A338225, A226205. Sequence in context: A119739 A163579 A290401 * A238663 A141966 A050833 Adjacent sequences: A341925 A341926 A341927 * A341929 A341930 A341931 KEYWORD nonn,easy AUTHOR Burak Muslu, Feb 23 2021 STATUS approved

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Last modified June 16 08:44 EDT 2024. Contains 373423 sequences. (Running on oeis4.)