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A111156 Numbers that look the same when printed upside down. 3
0, 8, 69, 88, 96, 609, 689, 808, 888, 906, 986, 6009, 6699, 6889, 6969, 8008, 8698, 8888, 8968, 9006, 9696, 9886, 9966, 60009, 60809, 66099, 66899, 68089, 68889, 69069, 69869, 80008, 80808, 86098, 86898, 88088, 88888, 89068, 89868, 90006, 90806, 96096, 96896, 98086, 98886, 99066, 99866, 600009 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Numbers with 1's are excluded.

Numbers written with digits 0,6,8,9, with 6 and 9 interchanged when reversed. - Robert Israel, Jul 02 2018

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

MAPLE

f:= proc(n) local L, Lp, nl;

   L:= subs(1=6, 2=8, 3=9, convert(n, base, 4));

   nl:= nops(L);

   Lp:= subs([6=9, 9=6], L);

   add(Lp[-i]*10^(i-1), i=1..nl)+add(L[i]*10^(nl+i-1), i=1..nl);

end proc:

g:= proc(n) local L, Lp, nl;

   L:= subs(1=6, 2=8, 3=9, convert(n, base, 4));

   nl:= nops(L);

   Lp:= subs([6=9, 9=6], L);

   seq(add(Lp[-i]*10^(i-1), i=1..nl)+x*10^nl+add(L[i]*10^(nl+i), i=1..nl), x=[0, 8]);

end proc:

0, 8, seq(op([seq(f(n), n=4^i..4^(i+1)-1), seq(g(n), n=4^i..4^(i+1)-1)]), i=0..2); # Robert Israel, Jul 02 2018

PROG

{-Haskell-} main=print$"0":concat[concat[[reverse(reverse(map f x)++z++x)|x<-y]|z<-["", "0"]]|y<-s(iterate i"6")]; f '0'='0'; f '6'='9'; f '8'='8'; f '9'='6'; i('0':x)='6':x; i('6':x)='8':x; i('8':x)='9':x; i('9':x)='0':i x; i""="6"; s(x:y@(z:_))=let w:v=s y in if length x==length z then(x:w):v else[x]:w:v

CROSSREFS

Cf. strobogrammatic numbers A000787. If 8's are excluded we get A111065.

Sequence in context: A303010 A087487 A178368 * A297633 A152279 A015575

Adjacent sequences:  A111153 A111154 A111155 * A111157 A111158 A111159

KEYWORD

base,easy,nonn

AUTHOR

Paul Stoeber (pstoeber(AT)uni-potsdam.de), Oct 09 2005

EXTENSIONS

Corrected by Robert Israel, Jul 02 2018

STATUS

approved

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Last modified January 24 10:24 EST 2020. Contains 331193 sequences. (Running on oeis4.)