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Greatest digit of n * least digit of n.
5

%I #16 Aug 18 2024 23:41:08

%S 1,4,9,16,25,36,49,64,81,0,1,2,3,4,5,6,7,8,9,0,2,4,6,8,10,12,14,16,18,

%T 0,3,6,9,12,15,18,21,24,27,0,4,8,12,16,20,24,28,32,36,0,5,10,15,20,25,

%U 30,35,40,45,0,6,12,18,24,30,36,42,48,54,0,7,14,21,28,35,42,49,56,63,0,8

%N Greatest digit of n * least digit of n.

%C a(101) = 0 and A111707(101) = 1, but all previous terms match.

%C a(n) = A169669(n) for n <= 100.

%H Reinhard Zumkeller, <a href="/A115300/b115300.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A054054(n)*A054055(n). - _Reinhard Zumkeller_, Apr 29 2015

%e a(3) = 3 * 3 = 9, a(232) = 3 * 2 = 6, a(1889009898) = 9 * 0 = 0.

%t Array[Max[#] * Min[#] &@ IntegerDigits[#] &, 81] (* _James C. McMahon_, Aug 18 2024 *)

%o (Haskell)

%o a115300 n = a054054 n * a054055 n -- _Reinhard Zumkeller_, Apr 29 2015

%o (Python)

%o def a(n): d = list(map(int, str(n))); return max(d) * min(d)

%o print([a(n) for n in range(1, 82)]) # _Michael S. Branicky_, Dec 12 2023

%o (PARI) a(n) = my(d=digits(n)); vecmin(d)*vecmax(d); \\ _Michel Marcus_, Aug 18 2024

%Y Cf. A037904 (greatest-least), A115299 (greatest+least), A111707.

%Y Cf. A054054, A054055, A169669.

%K base,nonn,look

%O 1,2

%A _Rick L. Shepherd_, Jan 20 2006