[seqfan] Re: A002061

[Richard Mathar]

http://list.seqfan.eu/pipermail/seqfan/2010-July/005321.html

vl> For the controll: %F A002061 a(n)=2*n+a(n-1)-4 (with a(1)=1) [From Vincenzo Librandi
vl> (vincenzo.librandi(AT)tin.it), Jul 13 2010]
vl> %e A002061 For n=2, a(2)=2*2+1-4=1: n=3, a(3)=2*3+1-4=3; n=4,
vl> a(4)=2*4+3-4=7 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it),
vl> Jul 13 2010]	
vl> RegardsVincenzo 

This is incorrect:
a(n)=n^2-n+1
->
a(n-1)=(n-1)^2-(n-1)+1
      =n^2-3n+3
      =n^2-n+1-2n+2
      =a(n)-2n+2

(Of course, the a(n)=a(n-1)+2n formula that is part of the
current entry is also incorrect.)

The examples proposed above are also incorrect. Note that a(0)=1, a(1)=1, a(2)=3
which is absolutely evident from just reading the sequence given the offset.