A034056 - OEIS

A034056

Numbers with multiplicative digital root value 9.

9, 19, 33, 91, 119, 133, 191, 313, 331, 911, 1119, 1133, 1191, 1313, 1331, 1911, 3113, 3131, 3311, 9111, 11119, 11133, 11191, 11313, 11331, 11911, 13113, 13131, 13311, 19111, 31113, 31131, 31311, 33111, 91111, 111119, 111133, 111191, 111313, 111331

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OFFSET

1,1

COMMENTS

Numbers with one 9 or two 3s, and zero or more 1s. - Daniel Forgues, Oct 09 2011

LINKS

Table of n, a(n) for n=1..40.

Eric Weisstein's World of Mathematics, Multiplicative Digital Root

Index entries for 10-automatic sequences.

FORMULA

There are n(n+1)(n+2)/6 elements up to 10^n, so a(n) is about 10^sqrt(6n).

CROSSREFS

Cf. A031347.

Cf. A034048, A002275, A034049, A034050, A034051, A034052, A034053, A034054, A034055, A034056 (numbers having multiplicative digital roots 0-9).

Sequence in context: A250663 A274590 A051811 * A195042 A157034 A198590

Adjacent sequences: A034053 A034054 A034055 * A034057 A034058 A034059

KEYWORD

nonn,base,easy,changed

AUTHOR

Patrick De Geest, Sep 15 1998

STATUS

approved