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Positive numbers whose product of digits is 7 times their sum.
10

%I #15 Sep 11 2022 09:35:27

%S 279,297,357,375,537,573,729,735,753,792,927,972,1447,1474,1744,4147,

%T 4174,4417,4471,4714,4741,7144,7414,7441,11367,11376,11637,11673,

%U 11736,11763,12247,12274,12427,12472,12724,12742,13167,13176,13617,13671

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

%H Harry J. Smith, <a href="/A062384/b062384.txt">Table of n, a(n) for n = 1..500</a>

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

%o (PARI) isok(n) = my(d=digits(n)); vecprod(d)==7*vecsum(d) \\ _Mohammed Yaseen_, Sep 09 2022

%o (Python)

%o from math import prod

%o def ok(n): d = list(map(int, str(n))); return n > 0 and prod(d) == 7*sum(d)

%o print([k for k in range(14000) if ok(k)]) # _Michael S. Branicky_, Sep 09 2022

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

%K nonn,base,easy

%O 1,1

%A _Amarnath Murthy_, Jun 27 2001

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