A354210 a(n) = floor(sqrt(Fibonacci(n+1)*Fibonacci(n))).

0, 1, 1, 2, 3, 6, 10, 16, 26, 43, 69, 113, 183, 296, 479, 775, 1255, 2031, 3286, 5318, 8605, 13923, 22528, 36452, 58981, 95433, 154414, 249847, 404261, 654109, 1058371, 1712480, 2770851, 4483332, 7254184, 11737516, 18991701, 30729217, 49720919, 80450136, 130171055, 210621192

Offset

0,4

Links

Table of n, a(n) for n=0..41.

P. Ferraro, Problem B-1288, Fibonacci Q., 59 (No. 2, May 2021) p. 177.

Formula

a(n) = floor(sqrt(A001654(n))).

Mathematica

a[n_] := Floor[Sqrt[Fibonacci[n + 1] * Fibonacci[n]]]; Array[a, 42, 0] (* Amiram Eldar, May 19 2022 *)

Prog

(PARI) a(n) = sqrtint(fibonacci(n+1)*fibonacci(n));
(Python)
from math import prod
from gmpy2 import isqrt, fib2
def A354210(n): return int(isqrt(prod(fib2(n+1)))) # Chai Wah Wu, May 19 2022

Crossrefs

Cf. A000045, A001654, A061287, A199575.

Sequence in context: A201077 A355383 A023655 * A023561 A243735 A034419

Adjacent sequences: A354207 A354208 A354209 * A354211 A354212 A354213

Keyword

nonn

Author

Michel Marcus, May 19 2022

Status

approved