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

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

Offset: 1

Author

A. D. Skovgaard, Apr 24 2016

Keywords

• base
• easy
• nonn

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

Crossrefs

Cf. A000787, A045574.

Programs

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