Editing Harshad number (section)

== Examples ==
* The number 18 is a harshad number in [[base 10]], because the sum of the digits 1 and 8 is 9, and 18 is [[divisible]] by 9.
* The [[1729 (number)|Hardy–Ramanujan number (1729)]] is a harshad number in base 10, since it is divisible by 19, the sum of its digits (1729 = 19 × 91).
* The number 19 is not a harshad number in base 10, because the sum of the digits 1 and 9 is 10, and 19 is not divisible by 10.
*In base 10, every [[natural number]] expressible in the form 9R<sub>''n''</sub>''a''<sub>''n''</sub>, where the number R<sub>''n''</sub> consists of ''n'' copies of the single digit 1, ''n'' > 0, and ''a''<sub>''n''</sub> is a positive integer less than 10<sup>''n''</sup> and multiple of ''n'', is a harshad number. (R. D’Amico, 2019).  The number 9R<sub>3</sub>''a''<sub>3</sub> = 521478, where R<sub>3</sub> = 111, ''n'' = 3 and ''a''<sub>3</sub> = 3×174 = 522, is a harshad number; in fact, we have: 521478/(5+2+1+4+7+8) = 521478/27 = 19314.<ref> Rosario D'Amico, A method to generate Harshad numbers, in Journal of Mathematical Economics and Finance, vol. 5, n. 1, giugno 2019, p. 19-26.</ref>
*Harshad numbers in base 10 form the [[integer sequence|sequence]]:
*: [[1 (number)|1]], [[2 (number)|2]], [[3 (number)|3]], [[4 (number)|4]], [[5 (number)|5]], [[6 (number)|6]], [[7 (number)|7]], [[8 (number)|8]], [[9 (number)|9]], [[10 (number)|10]], [[12 (number)|12]], [[18 (number)|18]], [[20 (number)|20]], [[21 (number)|21]], [[24 (number)|24]], [[27 (number)|27]], [[30 (number)|30]], [[36 (number)|36]], [[40 (number)|40]], [[42 (number)|42]], [[45 (number)|45]], [[48 (number)|48]], [[50 (number)|50]], [[54 (number)|54]], [[60 (number)|60]], [[63 (number)|63]], [[70 (number)|70]], [[72 (number)|72]], [[80 (number)|80]], [[81 (number)|81]], [[84 (number)|84]], [[90 (number)|90]], [[100 (number)|100]], [[102 (number)|102]], [[108 (number)|108]], [[110 (number)|110]], [[111 (number)|111]], [[112 (number)|112]], [[114 (number)|114]], [[117 (number)|117]], [[120 (number)|120]], [[126 (number)|126]], [[132 (number)|132]], [[133 (number)|133]], [[135 (number)|135]], [[140 (number)|140]], [[144 (number)|144]], [[150 (number)|150]], [[152 (number)|152]], [[153 (number)|153]], [[156 (number)|156]], [[162 (number)|162]], [[171 (number)|171]], [[180 (number)|180]], [[190 (number)|190]], [[192 (number)|192]], [[195 (number)|195]], [[198 (number)|198]], [[200 (number)|200]], ...  {{OEIS|id=A005349}}.
*All integers between [[0 (number)|zero]] and {{mvar|n}} are {{mvar|n}}-harshad numbers.