The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A333907 For n >= 1, a(n) = Sum_{k=1..n} prevfib(k) + nextfib(k) - 2*k, where prevfib(k) is the largest Fibonacci number < k, nextfib(k) is the smallest Fibonacci number > k. 0
 0, 0, 1, 1, 2, 3, 2, 4, 7, 8, 7, 4, 7, 13, 17, 19, 19, 17, 13, 7, 12, 23, 32, 39, 44, 47, 48, 47, 44, 39, 32, 23, 12, 20, 39, 56, 71, 84, 95, 104, 111, 116, 119, 120, 119, 116, 111, 104, 95, 84, 71, 56, 39, 20, 33, 65, 95, 123, 149, 173, 195, 215, 233, 249, 263, 275 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,5 LINKS EXAMPLE a(1) = (0 + 2 - 2*1) = 0; a(2) = (0 + 2 - 2*1) + (1 + 3 - 2*2) = 0; a(3) = (0 + 2 - 2*1) + (1 + 3 - 2*2) + (2 + 5 - 2*3) = 1; a(4) = (0 + 2 - 2*1) + (1 + 3 - 2*2) + (2 + 5 - 2*3) + (3 + 5 - 2*4) = 1. PROG (PARI) isfib(k) = my(m=5*k^2); issquare(m-4) || issquare(m+4); nextfib(n) = my(k=n+1); while (!isfib(k), k++); k; prevfib(n) = my(k=n-1); while (!isfib(k), k--); k; a(n) = sum(k=1, n, prevfib(k) + nextfib(k) - 2*k); \\ Michel Marcus, Apr 10 2020 CROSSREFS Cf. A000045, A001076, A087172, A130473, A194029, A256654, A280514. Sequence in context: A132439 A338902 A116217 * A274486 A227961 A108838 Adjacent sequences:  A333904 A333905 A333906 * A333908 A333909 A333910 KEYWORD nonn AUTHOR Ctibor O. Zizka, Apr 09 2020 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified August 10 13:12 EDT 2022. Contains 356039 sequences. (Running on oeis4.)