A376257 - OEIS

%I #24 Dec 10 2024 10:26:23

%S 0,0,0,0,0,0,0,0,0,10,-10,10,-10,10,-10,10,-10,10,-10,20,19,18,17,16,

%T 15,14,13,12,11,30,-28,26,-24,22,-20,18,-16,14,-12,40,37,34,31,28,25,

%U 22,19,16,13,50,-46,42,-38,34,-30,26,-22,18,-14,60,55,50,45,40,35,30,25,20,15,70,-64,58

%N a(n) = (n - c(n))*(-1)^c(n), where c(n) is the product of the digits of n (A007954).

%C There is an interesting pattern on the graph of the sequence.

%H Paolo Xausa, <a href="/A376257/b376257.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = (n-A007954(n)) * (-1)^A007954(n).

%e For n = 129: 1*2*9=18. So a(n) = (129-18)*(-1)^18 = 111.

%t A376257[n_] := (n - #)*(-1)^# & [Times @@ IntegerDigits[n]];

%t Array[A376257, 100] (* _Paolo Xausa_, Dec 10 2024 *)

%Y Cf. A007954, A070565.

%K sign,base,look

%O 1,10

%A _Stuart Coe_, Sep 17 2024