A119249 Indices of Fibonacci numbers in A081952.

4, 7, 10, 17, 22, 31, 41, 47, 49, 71, 71, 98, 119, 161, 169, 191, 191, 239, 239, 239, 338, 338, 338, 431, 431, 449, 529, 599, 649, 649, 769, 769, 769, 769, 769, 769, 1009, 1009, 1009, 1409, 1441, 1441, 1441, 1441, 1729, 1889, 1889, 1889, 1889, 2159, 2209, 2209, 2209, 2591, 2642, 2642

Offset

1,1

Links

Table of n, a(n) for n=1..56.

Formula

A081952(n) = F(a(n)), where F(k) is the k-th Fibonacci number.

a(n) = the smallest k>3 such that A086435(A000045(k)-1)>=n. - Max Alekseyev, Apr 23 2010

Example

A081952(4) = 1597 and 1597 is the 17th Fibonacci number, so a(4) = 17.

Mathematica

f[n_, m_, 0] := n == 1; f[n_, m_, d_] := (b = False; l = Select[Divisors[n], #>=m&]; For[i = 1, i <= Length[l], i++, k = l[[i]]; If[f[n / k, k + 1, d - 1], b = True; Break[]]]; b); Do[x = 3; While[ !f[Fibonacci[x] - 1, 2, y], x++ ]; Print[x], {y, 1, 50}]

Crossrefs

Cf. A000045, A000071, A081952, A086435.

Sequence in context: A310715 A310716 A310717 * A071415 A310718 A310719

Adjacent sequences: A119246 A119247 A119248 * A119250 A119251 A119252

Keyword

nonn

Author

Ryan Propper, Jul 22 2006

Extensions

a(24)-a(26) from Max Alekseyev, Apr 23 2010

a(27)-a(56) from Amiram Eldar, Jun 24 2023

Status

approved