

A034054


Numbers with multiplicative digital root value 7.


13



7, 17, 71, 117, 171, 711, 1117, 1171, 1711, 7111, 11117, 11171, 11711, 17111, 71111, 111117, 111171, 111711, 117111, 171111, 711111, 1111117, 1111171, 1111711, 1117111, 1171111, 1711111, 7111111, 11111117, 11111171, 11111711, 11117111
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OFFSET

1,1


COMMENTS

Numbers with one 7, and zero or more 1s.  Daniel Forgues, Oct 09 2011


LINKS

Table of n, a(n) for n=1..32.
Eric Weisstein's World of Mathematics, Multiplicative Digital Root


FORMULA

There are n(n+1)/2 elements up to 10^n, so a(n) is about 10^sqrt(2n).


CROSSREFS

Cf. A031347.
Cf. A034048, A002275, A034049, A034050, A034051, A034052, A034053, A034054, A034055, A034056 (numbers having multiplicative digital roots 09).
Sequence in context: A118431 A051809 A242907 * A120876 A216073 A086870
Adjacent sequences: A034051 A034052 A034053 * A034055 A034056 A034057


KEYWORD

nonn,base


AUTHOR

Patrick De Geest, Sep 15 1998.


STATUS

approved



