0,2

a(n)=5*(8^n-1)/7.

a(n)=8*a(n-1)+5 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 30 2009]

Octal...............decimal

0........................0

5........................5

55......................45

555....................365

5555..................2925

55555................23405

555555..............187245

5555555............1497965

55555555..........11983725

555555555.........95869805

5555555555.......766958445

etc. ...............etc.

For n=2, a(2)=8*0+5=5; n=3, a(3)=8*5+5=45; n=4, a(4)=8*45+5=365 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 30 2009]

seq(5*(8^n-1)/7, n=0..20);

Sequence in context: A079139 A081070 A043025 this_sequence A001260 A088505 A067403

Adjacent sequences: A125833 A125834 A125835 this_sequence A125837 A125838 A125839

easy,nonn,new

Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 03 2007