A102251 -id:A102251 - cp's OEIS frontend

A248131 Start with a(0) = 1, then a(n) = three times the n-th digit of the sequence.

1, 3, 9, 27, 6, 21, 18, 6, 3, 3, 24, 18, 9, 9, 6, 12, 3, 24, 27, 27, 18, 3, 6, 9, 6, 12, 6, 21, 6, 21, 3, 24, 9, 18, 27, 18, 3, 6, 18, 6, 3, 18, 6, 3, 9, 6, 12, 27, 3, 24, 6, 21, 3, 24, 9, 18, 3, 24, 18, 9, 3, 24, 18, 9, 27, 18, 3, 6, 6, 21, 9, 6, 12, 18, 6, 3, 9, 6, 12, 27

Offset: 0

M. F. Hasler, Oct 02 2014

A (more natural?) variant of A248128, using the same rule but the smallest nontrivial initial value a(0)=1 instead of 50. However, none of the digits 0 and 5 can appear in the sequence if they don't appear in a(0), which motivates A248128(0)=50. See A248153 for a variant using multiples of 7 instead of 3.

All terms a(n) with index n>0 are divisible by 3, the sequence a(n)/3 yields exactly the individual digits of this sequence.

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Cf. A248128-A248130.

Cf. A102251.

a248131 n = a248131_list !! n
a248131_list = 1 : (map (* 3) $
               concatMap (map (read . return) . show) a248131_list)
-- Reinhard Zumkeller, Oct 02 2014

a(n,s=1,d=[])={for(i=1,n,print1(s",");d=concat(d,if(s,digits(s)));s=3*d[1];d=vecextract(d,"^1"));s}

A102256 Begin with 1, multiply each digit by 2, separate the digits.

Original entry on oeis.org

1, 2, 4, 8, 1, 6, 2, 1, 2, 4, 2, 4, 8, 4, 8, 1, 6, 8, 1, 6, 2, 1, 2, 1, 6, 2, 1, 2, 4, 2, 4, 2, 1, 2, 4, 2, 4, 8, 4, 8, 4, 2, 4, 8, 4, 8, 1, 6, 8, 1, 6, 8, 4, 8, 1, 6, 8, 1, 6, 2, 1, 2, 1, 6, 2, 1, 2, 1, 6, 8, 1, 6, 2, 1, 2, 1, 6, 2, 1, 2, 4, 2, 4, 2, 1, 2, 4, 2, 4, 2, 1, 2, 1, 6, 2, 1, 2, 4, 2, 4, 2, 1, 2, 4, 2

Offset: 1

Alexandre Wajnberg and Eric Angelini, Feb 19 2005

Same digits as A061581 and A102251 but separating all digits.

			Read a(4)=8 which produces, doing 8*2=16 ["1" & "6"], a(5)=1 & a(6)=6.
Now read a(5)=1 which produces [a(6) is already written] a(7)=2 because 1*2=2.
Now read a(6)=6 which produces [a(7) is already written] a(8)=1 & a(9)=2 because 6*2=12 ["1" & "2"].

Cf. A061581, A102251.

Flatten[ NestList[ Function[x, Flatten[ IntegerDigits[ 2IntegerDigits[ x]]]], 1, 14]] (* Robert G. Wilson v, Feb 21 2005 *)

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

cp's OEIS Frontend

A248131 Start with a(0) = 1, then a(n) = three times the n-th digit of the sequence.

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