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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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..72.

Jean-Marie 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(k-1)+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

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Last modified May 18 10:19 EDT 2021. Contains 343995 sequences. (Running on oeis4.)