A129287 Number of Harshad numbers between 10^n and 10^n + 100.

29, 30, 31, 29, 30, 28, 29, 30, 30, 29, 28, 28, 29, 30, 30, 29, 29, 28, 30, 30, 31, 29, 29, 28, 29, 30, 30, 29, 28, 28, 29, 30, 31, 29, 29, 28, 30, 30, 30, 29, 29, 28, 29, 30, 30, 29, 28, 28, 30, 30, 31, 29, 29, 28, 29, 30, 30, 29, 29, 28, 29, 30, 30, 29, 29, 28, 30, 30, 31

Offset

3,1

Comments

Will every term be between 28 and 31 inclusive?

References

Jason Earls, Red Zen, Lulu Press, NY, 2006, pp. 145-146. ISBN: 978-1-4303-2017-3.

Links

Amiram Eldar, Table of n, a(n) for n = 3..10000

Example

There are exactly 29 Harshad numbers between 1000 and 1100, so the first term is 29.

Mathematica

a[n_] := Count[Range[10^n, 10^n + 100], _?(Divisible[#, Plus @@ IntegerDigits[#]] &)]; Array[a, 70, 3] (* Amiram Eldar, Jan 27 2021 *)

Crossrefs

Cf. A005349.

Sequence in context: A210267 A210309 A165850 * A007642 A353004 A295749

Adjacent sequences: A129284 A129285 A129286 * A129288 A129289 A129290

Keyword

nonn,base

Author

Jason Earls, May 26 2007

Status

approved