login
A119249
Indices of Fibonacci numbers in A081952.
1
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
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
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