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

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

Offset: 1

Author

Amarnath Murthy, Apr 02 2003

Keywords

• nonn

Examples

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

Links

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

Crossrefs

Subset of A000045.

Cf. A000071, A001222, A081952.

Programs

Maple

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

PARI

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

Formula

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

Extensions

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

Corrected and extended by Max Alekseyev, Apr 22 2010