

A086706


Number of Niven numbers less than or equal to n.


1



1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 19, 19, 20, 20, 20, 21, 21, 21, 22, 22, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 25, 25, 25, 26, 26, 26, 26, 26, 26, 26, 27, 27, 28
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..72.
JeanMarie De Koninck and Nicolas Doyon, Large and Small Gaps Between Consecutive Niven Numbers, J. Integer Seqs., Vol. 6, 2003, Article 03.2.5.


FORMULA

a(n)=(c+o(1))*n/log(n) where c=14/27*log(10)=1.1939330111820977620834029765030036632....


PROG

(PARI)
s(k)=if(k<1, 0, if(k%10, s(k1)+1, s(k/10)));
a(n)=sum(k=1, n, if(k%s(k), 0, 1));


CROSSREFS

Cf. A005349.
Sequence in context: A179622 A285757 A136687 * A100470 A071604 A337769
Adjacent sequences: A086703 A086704 A086705 * A086707 A086708 A086709


KEYWORD

nonn,base


AUTHOR

Benoit Cloitre, Jul 28 2003


STATUS

approved



