# [seqfan] Re: Problem with A086224 cross refs

Richard Guy rkg at cpsc.ucalgary.ca
Fri Oct 21 21:18:09 CEST 2011

```Note that these sequences satisfy the recurrence

a(n) = 3*a(n-1) - 2a(n-2) whose characteristic
polynomial is  (x - 1)(x - 2) and solution  A + B*2^n,

A = 2*a(0) - a(1),  B = a(1) - a(0)    R.

On Fri, 21 Oct 2011, Jeremy Gardiner wrote:

> A086224    a(0) = 6, a(n+1) = 2*a(n) + 1 (or a(n)=-1+7*2^n)
> 6,13,27,55,111,223,447,895,1791,3583, ...
>
> CROSSREFS
> a(0) = 2 gives A055010 except for initial terms  - OK (better A153893)
> a(0) = 4 gives A052549 except initial terms      - OK (better A153894)
> a(0) = 6 gives A086224                           - OK
> a(0) = 8 gives A052549 except initial terms      - Actually A052996
> a(0) = 10 gives A086225                          - OK
> a(0) = 12 gives A086226                          - Not in the OEIS
> a(0) = 14 gives A086227                          - Actually A196305
> a(0) = 16 gives A086228                          - Not in the OEIS
> a(0) = 18 gives A086229                          - Not in the OEIS
>
> Also a(0) = 20 gives A171389
>
> It appears some sequences may have been deleted/rejected and the A-numbers
> re-used: I can correct the cross refs - but how about adding the missing
> sequences?
>
> Jeremy Gardiner
>
>
>
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>
>

```