A117079 a(1) = 1; a(n) = 2*a(n-1) + (number of digits in a(n-1)).

1, 3, 7, 15, 32, 66, 134, 271, 545, 1093, 2190, 4384, 8772, 17548, 35101, 70207, 140419, 280844, 561694, 1123394, 2246795, 4493597, 8987201, 17974409, 35948826, 71897660, 143795328, 287590665, 575181339, 1150362687, 2300725384, 4601450778, 9202901566

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

1*2+1=3
3*2+1=7
7*2+1=15
15*2+2=3
etc.

Mathematica

a[1] = 1; a[n_] := a[n] = 2a[n - 1] + Floor[Log[10, a[n - 1]]] + 1 (* Robert G. Wilson v, Apr 20 2006 *)
RecurrenceTable[{a[1]==1, a[n]==2a[n-1]+IntegerLength[a[n-1]]}, a[n], {n, 40}] (* Harvey P. Dale, May 03 2011 *)
NestList[2#+IntegerLength[#]&, 1, 30] (* Harvey P. Dale, Oct 01 2012 *)

Crossrefs

Sequence in context: A132978 A336976 A368346 * A026745 A139333 A099444

Adjacent sequences: A117076 A117077 A117078 * A117080 A117081 A117082

Keyword

easy,nonn,base

Author

Zededarian Zee (Zededarian(AT)Gmail.com), Apr 19 2006

Extensions

More terms from Stefan Steinerberger, Jonathan Vos Post, Robert G. Wilson v and James Greene (jmg482(AT)psu.edu), Apr 20 2006. Also from Atilla Bora (borabanana(AT)gmail.com), Apr 23 2006

Status

approved