

A248153


Start with a(0)=10, then a(n) = 7 times the nth 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
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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 A332980 A246662
Adjacent sequences: A248150 A248151 A248152 * A248154 A248155 A248156


KEYWORD

nonn,base


AUTHOR

M. F. Hasler, Oct 02 2014


STATUS

approved



