A062384 Positive numbers whose product of digits is 7 times their sum.

279, 297, 357, 375, 537, 573, 729, 735, 753, 792, 927, 972, 1447, 1474, 1744, 4147, 4174, 4417, 4471, 4714, 4741, 7144, 7414, 7441, 11367, 11376, 11637, 11673, 11736, 11763, 12247, 12274, 12427, 12472, 12724, 12742, 13167, 13176, 13617, 13671

Offset: 1

Author

Amarnath Murthy, Jun 27 2001

Keywords

• nonn
• base
• easy

Examples

			1447 belongs to the sequence as (1*4*4*7)/(1+4+4+7) = 112/16 = 7.
		

Links

• Harry J. Smith, Table of n, a(n) for n = 1..500

Crossrefs

Cf. A011540, A034710, A062034, A062035, A062036, A062382, A062037, A062040, A062041, A062043, A062045.

Programs

PARI

isok(n) = my(d=digits(n)); vecprod(d)==7*vecsum(d) \\ Mohammed Yaseen, Sep 09 2022

Python

from math import prod
def ok(n): d = list(map(int, str(n))); return n > 0 and prod(d) == 7*sum(d)
print([k for k in range(14000) if ok(k)]) # Michael S. Branicky, Sep 09 2022

Extensions

Corrected and extended by Larry Reeves (larryr(AT)acm.org), Jul 06 2001