cp's OEIS Frontend

A088999 Flip 6,9 numbers: if number k contains decimal digit '6' or '9', then flip all occurrences of '6' to '9' and vice versa.

%I A088999 #13 Sep 07 2021 09:29:18
%S A088999 9,6,19,16,29,26,39,36,49,46,59,56,90,91,92,93,94,95,99,97,98,96,79,
%T A088999 76,89,86,60,61,62,63,64,65,69,67,68,66,109,106,119,116,129,126,139,
%U A088999 136,149,146,159,156,190,191,192,193,194,195,199,197,198,196,179,176,189
%N A088999 Flip 6,9 numbers: if number k contains decimal digit '6' or '9', then flip all occurrences of '6' to '9' and vice versa.
%C A088999 For digits d of n if d = 6 make it 9 else if d = 9 make it 6.
%C A088999 However, numbers containing neither digit 6 nor 9 are not terms (cf. A222251).
%o A088999 (PARI) flip69(n) = { for(x=1,n, y=x; v=0; f=0; ln =length(Str(x)); a = vector(ln); forstep(j=ln,1,-1, r = y%10; a[j]=r; if(r==6,a[j] = 9; f=1); if(r==9,a[j] = 6; f=1); y = floor(y/10); ); forstep(j=ln,1,-1, v=v+a[j]*10^(ln-j) ); if(f,print1(v",")); ) }
%o A088999 (Python)
%o A088999 def has69(s): return '6' in s or '9' in s
%o A088999 def flp69(s): return s.replace("6", "-").replace("9", "6").replace("-", "9")
%o A088999 def aupto(lim):
%o A088999     return [int(flp69(s)) for s in map(str, range(lim+1)) if has69(s)]
%o A088999 print(aupto(186)) # _Michael S. Branicky_, Sep 06 2021
%Y A088999 Cf. A171055, A222251.
%K A088999 nonn,base
%O A088999 1,1
%A A088999 _Cino Hilliard_, Nov 02 2003