This site is supported by donations to The OEIS Foundation.

 Please make a donation to keep the OEIS running. We are now in our 55th year. In the past year we added 12000 new sequences and reached 8000 citations (which often say "discovered thanks to the OEIS"). We need to raise money to hire someone to manage submissions, which would reduce the load on our editors and speed up editing. Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A242627 Number of divisors of n that are less than 10. 22
 9, 1, 2, 2, 3, 2, 4, 2, 4, 3, 3, 1, 5, 1, 3, 3, 4, 1, 5, 1, 4, 3, 2, 1, 6, 2, 2, 3, 4, 1, 5, 1, 4, 2, 2, 3, 6, 1, 2, 2, 5, 1, 5, 1, 3, 4, 2, 1, 6, 2, 3, 2, 3, 1, 5, 2, 5, 2, 2, 1, 6, 1, 2, 4, 4, 2, 4, 1, 3, 2, 4, 1, 7, 1, 2, 3, 3, 2, 4, 1, 5, 3, 2, 1, 6, 2 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS Number of numbers <= 9, dividing n; a(n) <= 9; a(2520*n) = 9; a(n) = (number of repdigit numbers in row n of triangle A242614) = sum(A202022(A242614(n,k)): k=1..A242622(n)), for n > 0. Periodic with period 2520. Each period there are 576 1s, 720 2s, 464 3s, 360 4s, 206 5s, 122 6s, 58 7s, 13 8s, and 1 9 (average 2.82...). - Charles R Greathouse IV, Sep 27 2015 LINKS Reinhard Zumkeller, Table of n, a(n) for n = 0..10000 Index entries for linear recurrences with constant coefficients, signature (-2,-4,-7,-11,-15,-20,-24,-27,-28,-27,-23,-17,-9,0,9,17,23,27,28,27,24,20,15,11,7,4,2,1). FORMULA G.f.: sum(j=1..9, 1/(1-x^j)). - Robert Israel, Jul 31 2014 MAPLE a:= n -> numboccur(0, map2(`modp`, n, [\$1..9])): map(a, [\$0..100]); # Robert Israel, Jul 31 2014 PROG (Haskell) a242627 n = length \$ filter ((== 0) . mod n) [1..9] (PARI) a(n)=1+sum(k=2, 9, n%k<1) \\ Zak Seidov, Jul 31 2014 CROSSREFS Cf. A165412. Sequence in context: A257437 A010166 A186116 * A289502 A010165 A177273 Adjacent sequences:  A242624 A242625 A242626 * A242628 A242629 A242630 KEYWORD nonn,easy AUTHOR Reinhard Zumkeller, Jul 16 2014 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified December 15 00:30 EST 2019. Contains 329988 sequences. (Running on oeis4.)