A102251 - OEIS

%I #10 Mar 29 2015 16:33:49

%S 1,2,4,8,16,2,12,4,2,4,8,4,8,16,8,16,2,12,16,2,12,4,2,4,2,12,4,2,4,8,

%T 4,8,4,2,4,8,4,8,16,8,16,8,4,8,16,8,16,2,12,16,2,12,16,8,16,2,12,16,2,

%U 12,4,2,4,2,12,4,2,4,2,12,16,2,12,4,2,4,2,12,4,2,4,8,4,8,4,2,4,8,4,8,4,2,4

%N Begin with 1, multiply each digit by 2.

%C Same digits as A061581 without the memory of the groupings of the preceding digits. A bunch of sequences can be produced with this rule: a(n)=d*k beginning with 1,2,3... for k=2,3,...

%H Reinhard Zumkeller, <a href="/A102251/b102251.txt">Table of n, a(n) for n = 0..10000</a>

%F d*2, beginning with 1

%e Read a(5)=16 which produces a(6)=2 because 1*2=2 and a(7)=12 because 6*2=12. Now read a(6)=2 which produces [a(7) is already written] a(8)=4 because 2*2=4.

%t Flatten[ NestList[ Function[x, Flatten[ FromDigits /@ 2IntegerDigits[ x]]], 1, 15]] (* _Robert G. Wilson v_, Feb 21 2005 *)

%o (Haskell)

%o a102251 n = a102251_list !! n

%o a102251_list = 1 : (map (* 2) $

%o                concatMap (map (read . return) . show) a102251_list)

%o -- _Reinhard Zumkeller_, Oct 02 2014

%Y Cf. A061581.

%Y Cf. A248131.

%K base,easy,nonn

%O 0,2

%A _Alexandre Wajnberg_ and _Eric Angelini_, Feb 18 2005

%E More terms from _Robert G. Wilson v_, Feb 21 2005