0,2

a(n)=3*(5^n-1)/4.

a(n)=5*a(n-1)+3 (with a(1)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 30 2009]

Base 5.................decimal

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

3.........................3

33.......................18

333......................93

3333....................468

33333..................2343

333333................11718

3333333...............58593

33333333.............292968

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

For n=2, a(2)=5*0+3=3; n=3, a(3)=5*3+3=18; n=4, a(4)=5*18+3=93 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 30 2009]

seq(3*(5^n-1)/4, n=0..21);

Sequence in context: A092691 A064671 A058409 this_sequence A129547 A081151 A132848

Adjacent sequences: A125830 A125831 A125832 this_sequence A125834 A125835 A125836

easy,nonn

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