A343680 Niven (or Harshad) numbers which when divided by sum of their digits, give a quotient which is a Zuckerman number.

1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 18, 21, 24, 27, 36, 42, 45, 48, 54, 63, 72, 81, 84, 108, 135, 198, 216, 324, 648, 1008, 1035, 1050, 1152, 1215, 1344, 1380, 1680, 1725, 2016, 2376, 2592, 2625, 2688, 2997, 3675, 3816, 3888, 5616, 5670, 6912, 10008, 10017, 10035, 10044

Offset: 1

Author

Bernard Schott, Apr 26 2021

Keywords

• nonn
• base

Comments

The first 24 terms of A114440 are the first 24 terms of this sequence, then A114440(25) = 162, while a(25) = 135.

Examples

			84 is a Niven number as 84/(8+4) = 7, 7/7 = 1 so 7 is a Zuckerman number, and 84 is a term.
108 is a Niven number as 108/(1+0+8) = 12, 12/(1*2) = 6 so 12 is a Zuckerman number, and 108 is a term.
		

Links

• Giovanni Resta, Zuckerman Numbers, Numbers Aplenty.

Crossrefs

Cf. A005349, A007602, A114440, A235507.

Programs

Mathematica

zuckQ[n_] := IntegerQ[n] && (prod = Times @@ IntegerDigits[n]) > 0 && Divisible[n, prod]; Select[Range[10^4], zuckQ[#/Plus @@ IntegerDigits[#]] &] (* Amiram Eldar, Apr 26 2021 *)

PARI

isz(n) = my(p=vecprod(digits(n))); p && !(n % p); \\ A007602
isok(n) = my(s=sumdigits(n)); !(n%s) && isz(n/s); \\ Michel Marcus, Apr 26 2021

Extensions

More terms from Michel Marcus, Apr 26 2021