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A248131 Start with a(0) = 1, then a(n) = three times the n-th 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 (list; graph; refs; listen; history; text; internal format)
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. A248128-A248130.

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

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Last modified July 5 20:21 EDT 2020. Contains 335473 sequences. (Running on oeis4.)