A102260 Begin with 5, multiply each digit by 2, keeping the memory of the groupings of the preceding digits.

5, 10, 20, 40, 80, 160, 2120, 4240, 8480, 168160, 212162120, 4242124240, 8484248480, 16816848168160, 2121621216816212162120, 424212424212162124242124240, 8484248484242124248484248480

Offset

1,1

Links

Table of n, a(n) for n=1..17.

Formula

Apply the rule "d*2", beginning with 5

Example

Read a(5)=80 which produces a(6)=160 because 8*2=16 and 0*2=0.
Now read a(6)=160 which produces a(7)=2120 because 1*2=2, 6*2=12 and 0*2=0.
Read a(10)=168160 which produces the digits of a(11)=212162 AND the first three digits of a(12)=1204242 because 1*2=2, 6*2=12, 8*2=16, 1*2=2 AND 6*2=12 and 0*2=0

Mathematica

Flatten[ NestList[ Function[x, FromDigits[ Flatten[ IntegerDigits[2IntegerDigits[ x]]] ]], 5, 16]] (* Robert G. Wilson v, Feb 21 2005 *)

Crossrefs

Sequence in context: A323831 A020714 A146523 * A023383 A229171 A092407

Adjacent sequences: A102257 A102258 A102259 * A102261 A102262 A102263

Keyword

base,easy,nonn

Author

Alexandre Wajnberg and Eric Angelini, Feb 19 2005

Extensions

More terms from Robert G. Wilson v, Feb 21 2005

Edited by N. J. A. Sloane, Sep 06 2008 at the suggestion of R. J. Mathar

Status

approved