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 A272264 Numbers that become a different number when flipped upside down. 1
 6, 9, 16, 18, 19, 61, 66, 68, 81, 86, 89, 91, 98, 99, 106, 108, 109, 116, 118, 119, 161, 166, 168, 169, 186, 188, 189, 191, 196, 198, 199, 601, 606, 608, 611, 616, 618, 661, 666, 668, 669, 681, 686, 688, 691, 696, 698, 699, 801, 806, 809, 811, 816, 819, 861, 866, 868, 869, 881, 886, 889 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Although 2 and 5 flipped upside down on a digital clock are numbers, they are not permitted here. - David A. Corneth, May 22 2016 LINKS A. D. Skovgaard, Table of n, a(n) for n = 1..10000 PROG (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 CROSSREFS Cf. A000787, A045574. Sequence in context: A242183 A300564 A316050 * A316051 A316052 A316053 Adjacent sequences:  A272261 A272262 A272263 * A272265 A272266 A272267 KEYWORD base,easy,nonn AUTHOR A. D. Skovgaard, Apr 24 2016 STATUS approved

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Last modified October 22 22:34 EDT 2019. Contains 328335 sequences. (Running on oeis4.)