A081952 -id:A081952 - cp's OEIS frontend

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

Ryan Propper, Jul 22 2006

nonn

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

Cf. A000045, A000071, A081952, A086435.

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}]

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

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

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

A081953 Smallest Fibonacci number equal one plus the product of n (not necessarily distinct) integers > 1.

Original entry on oeis.org

3, 5, 13, 55, 1597, 28657, 28657, 121393, 2971215073, 2971215073, 2971215073, 7778742049, 308061521170129, 308061521170129, 135301852344706746049, 135301852344706746049, 1454489111232772683678306641953

Offset: 1

Amarnath Murthy, Apr 02 2003

nonn

			a(4)= 2*3*3*3 + 1 = 55.
a(5) = 2*3*3*7*19 + 1 = 1597.

Amiram Eldar, Table of n, a(n) for n = 1..60

Subset of A000045.

Cf. A000071, A001222, A081952.

for n from 1 to 14 do for fib from 2 to 5000 do f := combinat[fibonacci](fib)-1 ; allf := op(2,ifactors(f)) ; pow := 0 : for i from 1 to nops(allf) do pow := pow + op(2,op(i,allf)) ; od : if pow >= n then printf("%d,",f+1) ; break ; fi ; od : od ; # R. J. Mathar, Apr 13 2006

{ m=3; for(n=1,30, while(bigomega(fibonacci(m)-1)Max Alekseyev, Apr 22 2010

a(n) = A000045(k) for the smallest k such that A001222(A000045(k)-1) >= n.

More terms from R. J. Mathar, Apr 13 2006

Corrected and extended by Max Alekseyev, Apr 22 2010

cp's OEIS Frontend

A119249 Indices of Fibonacci numbers in A081952.

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