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 A056888 a(n) = number of k such that sum of digits of 9^k is 9n. 1
 2, 3, 2, 0, 4, 1, 3, 1, 1, 5, 2, 2, 3, 1, 0, 3, 6, 2, 3, 0, 0, 4, 1, 3, 1, 4, 1, 1, 0, 1, 3, 2, 3, 5, 1, 1, 3, 3, 2, 5, 0, 3, 3, 1, 1, 3, 2, 2, 0, 2, 1, 5, 2, 1, 1, 1, 1, 3, 4, 5, 1, 0, 1, 3, 2, 1, 2, 4, 5, 1, 1, 2, 1, 0, 1, 2, 4, 1, 2, 5, 0, 2, 4, 3, 2, 2, 1, 2, 2, 2, 0, 2, 3, 2, 1, 5, 1, 0, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Proposed by Mark Sapir, Math. Dept., Vanderbilt University, who remarks (August 2000) that he can prove that a(n) is always finite and that a(1) = 2. Values of a(n) for n>1 computed numerically by Michael Kleber, Sep 02 2000 and David W. Wilson, Sep 06 2000. All terms except the first are only conjectures. For the theorem that a(n) is always finite, see Senge-Straus and Stewart. - N. J. A. Sloane, Jan 06 2011 REFERENCES H. G. Senge and E. G. Straus, PV-numbers and sets of multiplicity, Periodica Math. Hungar., 3 (1971), 93-100. C. L. Stewart, On the representation of an integer in two different bases, J. Reine Angew. Math., 319 (1980), 63-72. LINKS EXAMPLE There are two powers of 9 with digit-sum 9, namely 9 and 81, so a(1) = 2. CROSSREFS Cf. A065999. Sequence in context: A165192 A104771 A307688 * A286297 A339451 A111182 Adjacent sequences: A056885 A056886 A056887 * A056889 A056890 A056891 KEYWORD nonn,base AUTHOR N. J. A. Sloane, Sep 05 2000 STATUS approved

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Last modified March 21 19:35 EDT 2023. Contains 361410 sequences. (Running on oeis4.)