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A248153 Start with a(0)=10, then a(n) = 7 times the n-th digit of the sequence. 1
10, 7, 0, 49, 0, 28, 63, 0, 14, 56, 42, 21, 0, 7, 28, 35, 42, 28, 14, 14, 7, 0, 49, 14, 56, 21, 35, 28, 14, 14, 56, 7, 28, 7, 28, 49, 0, 28, 63, 7, 28, 35, 42, 14, 7, 21, 35, 14, 56, 7, 28, 7, 28, 35, 42, 49, 14, 56, 49, 14, 56, 28, 63, 0, 14, 56, 42, 21, 49, 14, 56, 21, 35 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

This sequence was inspired by E. Angelini's post to the SeqFan list, cf. links.

a(0)=10 is the smallest possible choice to ensure that the digit 0 appears anywhere in the sequence. a(0)=1 would lead to the same sequence with the terms 0 removed.

By construction, all terms a(n), n>0, are divisible by 7, and a(n)/7 yields the sequence of digits of the (concatenated) terms of this sequence.

It is easy to show that the distance between two 0's is strictly increasing from one occurrence to the next one. Thus, the asymptotic density of terms and/or digits 0 is zero, and the sequence can never "enter a loop".

LINKS

Table of n, a(n) for n=0..72.

E. Angelini, Brute force density: triples and cubes, SeqFan list, Oct 01 2014

PROG

(PARI) a(n, s=10, m=7, d=[])={for(i=1, n, print1(s", "); d=concat(d, if(s, digits(s))); s=m*d[1]; d=vecextract(d, "^1")); s}

CROSSREFS

Cf. A248128, A248129, A248130, A248131.

Sequence in context: A248593 A038308 A185221 * A079166 A246662 A246651

Adjacent sequences:  A248150 A248151 A248152 * A248154 A248155 A248156

KEYWORD

nonn,base

AUTHOR

M. F. Hasler, Oct 02 2014

STATUS

approved

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Last modified October 14 18:28 EDT 2019. Contains 328022 sequences. (Running on oeis4.)