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A063896 a(n) = 2^Fibonacci(n) - 1. 13
0, 1, 1, 3, 7, 31, 255, 8191, 2097151, 17179869183, 36028797018963967, 618970019642690137449562111, 22300745198530623141535718272648361505980415 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

The recurrence can also be written a(n)+1 = (a(n-1)+1)*(a(n-2)+1) or log_p(a(n)+1) = log_p(a(n-1)+1) + log_p(a(n-2)+1), respectively. Setting a(1)=p-1 for any natural p>1, it follows that log_p(a(n)+1)=Fib(n). Hence any other sequence p^Fib(n)-1 could also serve as a valid solution to that recurrence, depending only on the value of the term a(1). - Hieronymus Fischer, Jun 27 2007

Written in binary, a(n) contains Fib(n) 1's (Fib(n)=A000045(n)). Thus the sequence converted to base-2 is A007088(a(n)) = 0, 1, 1, 11, 111, 11111, 11111111, ... . - Hieronymus Fischer, Jun 27 2007

LINKS

Table of n, a(n) for n=0..12.

FORMULA

The solution to the recurrence a(0) = 0; a(1) = 1; a(n) = a(n-1)*a(n-2) + a(n-1) + a(n-2).

a(n) = A000301(n+1) - 1. - R. J. Mathar, Apr 26 2007

a(n) = a(n-2)*2^ceiling(log_2(a(n-1))) + a(n-1) for n>1. - Hieronymus Fischer, Jun 27 2007

MATHEMATICA

a[0, k_] = 0; a[1, k_] = 1; a[n_, k_] := (k - 1)*a[n - 1, k]*a[n - 2, k] + a[n - 1, k] + a[n - 2, k]; Table[ a[n, 2], {n, 0, 14} ]

a=0; b=1; lst={a, b}; Do[c=a*b+a+b; AppendTo[lst, c]; a=b; b=c, {n, 3*3!}]; lst (* Vladimir Joseph Stephan Orlovsky, Sep 13 2009 *)

2^Fibonacci[Range[0, 15]]-1 (* Harvey P. Dale, May 20 2014 *)

RecurrenceTable[{a[0] == 0, a[1] == 1, a[n] == (a[n - 1] + 1)*(a[n - 2] + 1) - 1}, a[n], {n, 0, 12}] (* Ray Chandler, Jul 30 2015 *)

PROG

(PARI) a(n) = 2^fibonacci(n) - 1 \\ Charles R Greathouse IV, Oct 03 2016

CROSSREFS

Cf. A000045, A000301, A061107.

See A131293 for a base-10 analog with Fib(n) 1's.

Sequence in context: A073917 A030521 A105767 * A277028 A156895 A074047

Adjacent sequences:  A063893 A063894 A063895 * A063897 A063898 A063899

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Aug 29 2001

STATUS

approved

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Last modified May 25 05:56 EDT 2017. Contains 287012 sequences.