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A272264 Numbers that become a different number when flipped upside down. 1

%I #21 Dec 01 2018 19:58:53

%S 6,9,16,18,19,61,66,68,81,86,89,91,98,99,106,108,109,116,118,119,161,

%T 166,168,169,186,188,189,191,196,198,199,601,606,608,611,616,618,661,

%U 666,668,669,681,686,688,691,696,698,699,801,806,809,811,816,819,861,866,868,869,881,886,889

%N Numbers that become a different number when flipped upside down.

%C Although 2 and 5 flipped upside down on a digital clock are numbers, they are not permitted here. - _David A. Corneth_, May 22 2016

%H A. D. Skovgaard, <a href="/A272264/b272264.txt">Table of n, a(n) for n = 1..10000</a>

%o (PARI) is(n) = {my(d=digits(n),dr); if(d[#d]==0 || #setminus(Set(d),Set([0,1,6,8,9])) !=0, return(0), dr=vector(#d)); for(i=1,#d, dr[#d-i+1] = if(d[i]==6||d[i]==9,15-d[i],d[i]));dr!=d} \\ _David A. Corneth_, May 22 2016

%Y Cf. A000787, A045574.

%K base,easy,nonn

%O 1,1

%A _A. D. Skovgaard_, Apr 24 2016

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Last modified March 28 16:58 EDT 2024. Contains 371254 sequences. (Running on oeis4.)