

A248131


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


3



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
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OFFSET

0,2


COMMENTS

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.


LINKS

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


PROG

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


CROSSREFS

Cf. A248128A248130.
Cf. A102251.
Sequence in context: A317502 A213912 A070360 * A070346 A328754 A070345
Adjacent sequences: A248128 A248129 A248130 * A248132 A248133 A248134


KEYWORD

nonn,base


AUTHOR

M. F. Hasler, Oct 02 2014


STATUS

approved



